refactor(tool): migrate tool framework + all 18 built-in tools to Effect Schema (#23244)

2026-04-23 16:09:34 -04:00
parent 24892559ae
commit 3910a6e527
25 changed files with 1035 additions and 205 deletions
--- a/packages/opencode/src/tool/apply_patch.ts
+++ b/packages/opencode/src/tool/apply_patch.ts
@@ -1,6 +1,5 @@
-import z from "zod"
 import * as path from "path"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"
 import { Bus } from "../bus"
 import { FileWatcher } from "../file/watcher"
@@ -16,8 +15,8 @@ import { File } from "../file"
 import { Format } from "../format"
 import * as Bom from "@/util/bom"

-const PatchParams = z.object({
-  patchText: z.string().describe("The full patch text that describes all changes to be made"),
+export const Parameters = Schema.Struct({
+  patchText: Schema.String.annotate({ description: "The full patch text that describes all changes to be made" }),
 })

 export const ApplyPatchTool = Tool.define(
@@ -28,7 +27,7 @@ export const ApplyPatchTool = Tool.define(
    const format = yield* Format.Service
    const bus = yield* Bus.Service

-    const run = Effect.fn("ApplyPatchTool.execute")(function* (params: z.infer<typeof PatchParams>, ctx: Tool.Context) {
+    const run = Effect.fn("ApplyPatchTool.execute")(function* (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) {
      if (!params.patchText) {
        return yield* Effect.fail(new Error("patchText is required"))
      }
@@ -297,8 +296,8 @@ export const ApplyPatchTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: PatchParams,
-      execute: (params: z.infer<typeof PatchParams>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
    }
  }),
 )
--- a/packages/opencode/src/tool/bash.ts
+++ b/packages/opencode/src/tool/bash.ts
@@ -1,4 +1,4 @@
-import z from "zod"
+import { Schema } from "effect"
 import os from "os"
 import { createWriteStream } from "node:fs"
 import * as Tool from "./tool"
@@ -50,20 +50,16 @@ const FILES = new Set([
 const FLAGS = new Set(["-destination", "-literalpath", "-path"])
 const SWITCHES = new Set(["-confirm", "-debug", "-force", "-nonewline", "-recurse", "-verbose", "-whatif"])

-const Parameters = z.object({
-  command: z.string().describe("The command to execute"),
-  timeout: z.number().describe("Optional timeout in milliseconds").optional(),
-  workdir: z
-    .string()
-    .describe(
-      `The working directory to run the command in. Defaults to the current directory. Use this instead of 'cd' commands.`,
-    )
-    .optional(),
-  description: z
-    .string()
-    .describe(
+export const Parameters = Schema.Struct({
+  command: Schema.String.annotate({ description: "The command to execute" }),
+  timeout: Schema.optional(Schema.Number).annotate({ description: "Optional timeout in milliseconds" }),
+  workdir: Schema.optional(Schema.String).annotate({
+    description: `The working directory to run the command in. Defaults to the current directory. Use this instead of 'cd' commands.`,
+  }),
+  description: Schema.String.annotate({
+    description:
      "Clear, concise description of what this command does in 5-10 words. Examples:\nInput: ls\nOutput: Lists files in current directory\n\nInput: git status\nOutput: Shows working tree status\n\nInput: npm install\nOutput: Installs package dependencies\n\nInput: mkdir foo\nOutput: Creates directory 'foo'",
-    ),
+  }),
 })

 type Part = {
@@ -587,7 +583,7 @@ export const BashTool = Tool.define(
            .replaceAll("${maxLines}", String(Truncate.MAX_LINES))
            .replaceAll("${maxBytes}", String(Truncate.MAX_BYTES)),
          parameters: Parameters,
-          execute: (params: z.infer<typeof Parameters>, ctx: Tool.Context) =>
+          execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) =>
            Effect.gen(function* () {
              const cwd = params.workdir
                ? yield* resolvePath(params.workdir, Instance.directory, shell)
--- a/packages/opencode/src/tool/codesearch.ts
+++ b/packages/opencode/src/tool/codesearch.ts
@@ -1,10 +1,23 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import { HttpClient } from "effect/unstable/http"
 import * as Tool from "./tool"
 import * as McpExa from "./mcp-exa"
 import DESCRIPTION from "./codesearch.txt"

+export const Parameters = Schema.Struct({
+  query: Schema.String.annotate({
+    description:
+      "Search query to find relevant context for APIs, Libraries, and SDKs. For example, 'React useState hook examples', 'Python pandas dataframe filtering', 'Express.js middleware', 'Next js partial prerendering configuration'",
+  }),
+  tokensNum: Schema.Number.check(Schema.isGreaterThanOrEqualTo(1000))
+    .check(Schema.isLessThanOrEqualTo(50000))
+    .pipe(Schema.optional, Schema.withDecodingDefault(Effect.succeed(5000)))
+    .annotate({
+      description:
+        "Number of tokens to return (1000-50000). Default is 5000 tokens. Adjust this value based on how much context you need - use lower values for focused queries and higher values for comprehensive documentation.",
+    }),
+})
+
 export const CodeSearchTool = Tool.define(
  "codesearch",
  Effect.gen(function* () {
@@ -12,21 +25,7 @@ export const CodeSearchTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: z.object({
-        query: z
-          .string()
-          .describe(
-            "Search query to find relevant context for APIs, Libraries, and SDKs. For example, 'React useState hook examples', 'Python pandas dataframe filtering', 'Express.js middleware', 'Next js partial prerendering configuration'",
-          ),
-        tokensNum: z
-          .number()
-          .min(1000)
-          .max(50000)
-          .default(5000)
-          .describe(
-            "Number of tokens to return (1000-50000). Default is 5000 tokens. Adjust this value based on how much context you need - use lower values for focused queries and higher values for comprehensive documentation.",
-          ),
-      }),
+      parameters: Parameters,
      execute: (params: { query: string; tokensNum: number }, ctx: Tool.Context) =>
        Effect.gen(function* () {
          yield* ctx.ask({
@@ -45,7 +44,7 @@ export const CodeSearchTool = Tool.define(
            McpExa.CodeArgs,
            {
              query: params.query,
-              tokensNum: params.tokensNum || 5000,
+              tokensNum: params.tokensNum,
            },
            "30 seconds",
          )
--- a/packages/opencode/src/tool/edit.ts
+++ b/packages/opencode/src/tool/edit.ts
@@ -3,9 +3,8 @@
 // https://github.com/google-gemini/gemini-cli/blob/main/packages/core/src/utils/editCorrector.ts
 // https://github.com/cline/cline/blob/main/evals/diff-edits/diff-apply/diff-06-26-25.ts

-import z from "zod"
 import * as path from "path"
-import { Effect, Semaphore } from "effect"
+import { Effect, Schema, Semaphore } from "effect"
 import * as Tool from "./tool"
 import { LSP } from "../lsp"
 import { createTwoFilesPatch, diffLines } from "diff"
@@ -45,11 +44,15 @@ function lock(filePath: string) {
  return next
 }

-const Parameters = z.object({
-  filePath: z.string().describe("The absolute path to the file to modify"),
-  oldString: z.string().describe("The text to replace"),
-  newString: z.string().describe("The text to replace it with (must be different from oldString)"),
-  replaceAll: z.boolean().optional().describe("Replace all occurrences of oldString (default false)"),
+export const Parameters = Schema.Struct({
+  filePath: Schema.String.annotate({ description: "The absolute path to the file to modify" }),
+  oldString: Schema.String.annotate({ description: "The text to replace" }),
+  newString: Schema.String.annotate({
+    description: "The text to replace it with (must be different from oldString)",
+  }),
+  replaceAll: Schema.optional(Schema.Boolean).annotate({
+    description: "Replace all occurrences of oldString (default false)",
+  }),
 })

 export const EditTool = Tool.define(
@@ -63,7 +66,7 @@ export const EditTool = Tool.define(
    return {
      description: DESCRIPTION,
      parameters: Parameters,
-      execute: (params: z.infer<typeof Parameters>, ctx: Tool.Context) =>
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) =>
        Effect.gen(function* () {
          if (!params.filePath) {
            throw new Error("filePath is required")
--- a/packages/opencode/src/tool/glob.ts
+++ b/packages/opencode/src/tool/glob.ts
@@ -1,6 +1,5 @@
 import path from "path"
-import z from "zod"
-import { Effect, Option } from "effect"
+import { Effect, Option, Schema } from "effect"
 import * as Stream from "effect/Stream"
 import { InstanceState } from "@/effect"
 import { AppFileSystem } from "@opencode-ai/shared/filesystem"
@@ -9,6 +8,13 @@ import { assertExternalDirectoryEffect } from "./external-directory"
 import DESCRIPTION from "./glob.txt"
 import * as Tool from "./tool"

+export const Parameters = Schema.Struct({
+  pattern: Schema.String.annotate({ description: "The glob pattern to match files against" }),
+  path: Schema.optional(Schema.String).annotate({
+    description: `The directory to search in. If not specified, the current working directory will be used. IMPORTANT: Omit this field to use the default directory. DO NOT enter "undefined" or "null" - simply omit it for the default behavior. Must be a valid directory path if provided.`,
+  }),
+})
+
 export const GlobTool = Tool.define(
  "glob",
  Effect.gen(function* () {
@@ -17,15 +23,7 @@ export const GlobTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: z.object({
-        pattern: z.string().describe("The glob pattern to match files against"),
-        path: z
-          .string()
-          .optional()
-          .describe(
-            `The directory to search in. If not specified, the current working directory will be used. IMPORTANT: Omit this field to use the default directory. DO NOT enter "undefined" or "null" - simply omit it for the default behavior. Must be a valid directory path if provided.`,
-          ),
-      }),
+      parameters: Parameters,
      execute: (params: { pattern: string; path?: string }, ctx: Tool.Context) =>
        Effect.gen(function* () {
          const ins = yield* InstanceState.context
--- a/packages/opencode/src/tool/grep.ts
+++ b/packages/opencode/src/tool/grep.ts
@@ -1,5 +1,5 @@
 import path from "path"
-import z from "zod"
+import { Schema } from "effect"
 import { Effect, Option } from "effect"
 import { InstanceState } from "@/effect"
 import { AppFileSystem } from "@opencode-ai/shared/filesystem"
@@ -10,6 +10,16 @@ import * as Tool from "./tool"

 const MAX_LINE_LENGTH = 2000

+export const Parameters = Schema.Struct({
+  pattern: Schema.String.annotate({ description: "The regex pattern to search for in file contents" }),
+  path: Schema.optional(Schema.String).annotate({
+    description: "The directory to search in. Defaults to the current working directory.",
+  }),
+  include: Schema.optional(Schema.String).annotate({
+    description: 'File pattern to include in the search (e.g. "*.js", "*.{ts,tsx}")',
+  }),
+})
+
 export const GrepTool = Tool.define(
  "grep",
  Effect.gen(function* () {
@@ -18,11 +28,7 @@ export const GrepTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: z.object({
-        pattern: z.string().describe("The regex pattern to search for in file contents"),
-        path: z.string().optional().describe("The directory to search in. Defaults to the current working directory."),
-        include: z.string().optional().describe('File pattern to include in the search (e.g. "*.js", "*.{ts,tsx}")'),
-      }),
+      parameters: Parameters,
      execute: (params: { pattern: string; path?: string; include?: string }, ctx: Tool.Context) =>
        Effect.gen(function* () {
          const empty = {
--- a/packages/opencode/src/tool/invalid.ts
+++ b/packages/opencode/src/tool/invalid.ts
@@ -1,15 +1,16 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"

+export const Parameters = Schema.Struct({
+  tool: Schema.String,
+  error: Schema.String,
+})
+
 export const InvalidTool = Tool.define(
  "invalid",
  Effect.succeed({
    description: "Do not use",
-    parameters: z.object({
-      tool: z.string(),
-      error: z.string(),
-    }),
+    parameters: Parameters,
    execute: (params: { tool: string; error: string }) =>
      Effect.succeed({
        title: "Invalid Tool",
--- a/packages/opencode/src/tool/lsp.ts
+++ b/packages/opencode/src/tool/lsp.ts
@@ -1,5 +1,4 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"
 import path from "path"
 import { LSP } from "../lsp"
@@ -21,6 +20,17 @@ const operations = [
  "outgoingCalls",
 ] as const

+export const Parameters = Schema.Struct({
+  operation: Schema.Literals(operations).annotate({ description: "The LSP operation to perform" }),
+  filePath: Schema.String.annotate({ description: "The absolute or relative path to the file" }),
+  line: Schema.Number.check(Schema.isInt())
+    .check(Schema.isGreaterThanOrEqualTo(1))
+    .annotate({ description: "The line number (1-based, as shown in editors)" }),
+  character: Schema.Number.check(Schema.isInt())
+    .check(Schema.isGreaterThanOrEqualTo(1))
+    .annotate({ description: "The character offset (1-based, as shown in editors)" }),
+})
+
 export const LspTool = Tool.define(
  "lsp",
  Effect.gen(function* () {
@@ -29,12 +39,7 @@ export const LspTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: z.object({
-        operation: z.enum(operations).describe("The LSP operation to perform"),
-        filePath: z.string().describe("The absolute or relative path to the file"),
-        line: z.number().int().min(1).describe("The line number (1-based, as shown in editors)"),
-        character: z.number().int().min(1).describe("The character offset (1-based, as shown in editors)"),
-      }),
+      parameters: Parameters,
      execute: (
        args: { operation: (typeof operations)[number]; filePath: string; line: number; character: number },
        ctx: Tool.Context,
--- a/packages/opencode/src/tool/plan.ts
+++ b/packages/opencode/src/tool/plan.ts
@@ -1,6 +1,5 @@
-import z from "zod"
 import path from "path"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"
 import { Question } from "../question"
 import { Session } from "../session"
@@ -17,6 +16,8 @@ function getLastModel(sessionID: SessionID) {
  return undefined
 }

+export const Parameters = Schema.Struct({})
+
 export const PlanExitTool = Tool.define(
  "plan_exit",
  Effect.gen(function* () {
@@ -26,7 +27,7 @@ export const PlanExitTool = Tool.define(

    return {
      description: EXIT_DESCRIPTION,
-      parameters: z.object({}),
+      parameters: Parameters,
      execute: (_params: {}, ctx: Tool.Context) =>
        Effect.gen(function* () {
          const info = yield* session.get(ctx.sessionID)
--- a/packages/opencode/src/tool/question.ts
+++ b/packages/opencode/src/tool/question.ts
@@ -1,26 +1,25 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"
 import { Question } from "../question"
 import DESCRIPTION from "./question.txt"

-const parameters = z.object({
-  questions: z.array(Question.Prompt.zod).describe("Questions to ask"),
+export const Parameters = Schema.Struct({
+  questions: Schema.mutable(Schema.Array(Question.Prompt)).annotate({ description: "Questions to ask" }),
 })

 type Metadata = {
  answers: ReadonlyArray<Question.Answer>
 }

-export const QuestionTool = Tool.define<typeof parameters, Metadata, Question.Service>(
+export const QuestionTool = Tool.define<typeof Parameters, Metadata, Question.Service>(
  "question",
  Effect.gen(function* () {
    const question = yield* Question.Service

    return {
      description: DESCRIPTION,
-      parameters,
-      execute: (params: z.infer<typeof parameters>, ctx: Tool.Context<Metadata>) =>
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context<Metadata>) =>
        Effect.gen(function* () {
          const answers = yield* question.ask({
            sessionID: ctx.sessionID,
--- a/packages/opencode/src/tool/read.ts
+++ b/packages/opencode/src/tool/read.ts
@@ -1,5 +1,4 @@
-import z from "zod"
-import { Effect, Option, Scope } from "effect"
+import { Effect, Option, Schema, Scope } from "effect"
 import { createReadStream } from "fs"
 import * as path from "path"
 import { createInterface } from "readline"
@@ -19,10 +18,19 @@ const MAX_BYTES = 50 * 1024
 const MAX_BYTES_LABEL = `${MAX_BYTES / 1024} KB`
 const SAMPLE_BYTES = 4096

-const parameters = z.object({
-  filePath: z.string().describe("The absolute path to the file or directory to read"),
-  offset: z.coerce.number().describe("The line number to start reading from (1-indexed)").optional(),
-  limit: z.coerce.number().describe("The maximum number of lines to read (defaults to 2000)").optional(),
+// `offset` and `limit` were originally `z.coerce.number()` — the runtime
+// coercion was useful when the tool was called from a shell but serves no
+// purpose in the LLM tool-call path (the model emits typed JSON). The JSON
+// Schema output is identical (`type: "number"`), so the LLM view is
+// unchanged; purely CLI-facing uses must now send numbers rather than strings.
+export const Parameters = Schema.Struct({
+  filePath: Schema.String.annotate({ description: "The absolute path to the file or directory to read" }),
+  offset: Schema.optional(Schema.Number).annotate({
+    description: "The line number to start reading from (1-indexed)",
+  }),
+  limit: Schema.optional(Schema.Number).annotate({
+    description: "The maximum number of lines to read (defaults to 2000)",
+  }),
 })

 export const ReadTool = Tool.define(
@@ -140,7 +148,7 @@ export const ReadTool = Tool.define(
      return nonPrintableCount / bytes.length > 0.3
    }

-    const run = Effect.fn("ReadTool.execute")(function* (params: z.infer<typeof parameters>, ctx: Tool.Context) {
+    const run = Effect.fn("ReadTool.execute")(function* (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) {
      if (params.offset !== undefined && params.offset < 1) {
        return yield* Effect.fail(new Error("offset must be greater than or equal to 1"))
      }
@@ -275,8 +283,8 @@ export const ReadTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters,
-      execute: (params: z.infer<typeof parameters>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
    }
  }),
 )
--- a/packages/opencode/src/tool/registry.ts
+++ b/packages/opencode/src/tool/registry.ts
@@ -15,7 +15,9 @@ import { SkillTool } from "./skill"
 import * as Tool from "./tool"
 import { Config } from "../config"
 import { type ToolContext as PluginToolContext, type ToolDefinition } from "@opencode-ai/plugin"
+import { Schema } from "effect"
 import z from "zod"
+import { ZodOverride } from "@/util/effect-zod"
 import { Plugin } from "../plugin"
 import { Provider } from "../provider"
 import { ProviderID, type ModelID } from "../provider/schema"
@@ -120,9 +122,17 @@ export const layer: Layer.Layer<
        const custom: Tool.Def[] = []

        function fromPlugin(id: string, def: ToolDefinition): Tool.Def {
+          // Plugin tools define their args as a raw Zod shape. Wrap the
+          // derived Zod object in a `Schema.declare` so it slots into the
+          // Schema-typed framework, and annotate with `ZodOverride` so the
+          // walker emits the original Zod object for LLM JSON Schema.
+          const zodParams = z.object(def.args)
+          const parameters = Schema.declare<unknown>((u): u is unknown => zodParams.safeParse(u).success).annotate({
+            [ZodOverride]: zodParams,
+          })
          return {
            id,
-            parameters: z.object(def.args),
+            parameters,
            description: def.description,
            execute: (args, toolCtx) =>
              Effect.gen(function* () {
--- a/packages/opencode/src/tool/skill.ts
+++ b/packages/opencode/src/tool/skill.ts
@@ -1,15 +1,14 @@
 import path from "path"
 import { pathToFileURL } from "url"
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Stream from "effect/Stream"
 import { Ripgrep } from "../file/ripgrep"
 import { Skill } from "../skill"
 import * as Tool from "./tool"
 import DESCRIPTION from "./skill.txt"

-const Parameters = z.object({
-  name: z.string().describe("The name of the skill from available_skills"),
+export const Parameters = Schema.Struct({
+  name: Schema.String.annotate({ description: "The name of the skill from available_skills" }),
 })

 export const SkillTool = Tool.define(
@@ -21,7 +20,7 @@ export const SkillTool = Tool.define(
    return {
      description: DESCRIPTION,
      parameters: Parameters,
-      execute: (params: z.infer<typeof Parameters>, ctx: Tool.Context) =>
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) =>
        Effect.gen(function* () {
          const info = yield* skill.get(params.name)
          if (!info) {
--- a/packages/opencode/src/tool/task.ts
+++ b/packages/opencode/src/tool/task.ts
@@ -1,13 +1,12 @@
 import * as Tool from "./tool"
 import DESCRIPTION from "./task.txt"
-import z from "zod"
 import { Session } from "../session"
 import { SessionID, MessageID } from "../session/schema"
 import { MessageV2 } from "../session/message-v2"
 import { Agent } from "../agent/agent"
 import type { SessionPrompt } from "../session/prompt"
 import { Config } from "../config"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"

 export interface TaskPromptOps {
  cancel(sessionID: SessionID): void
@@ -17,17 +16,15 @@ export interface TaskPromptOps {

 const id = "task"

-const parameters = z.object({
-  description: z.string().describe("A short (3-5 words) description of the task"),
-  prompt: z.string().describe("The task for the agent to perform"),
-  subagent_type: z.string().describe("The type of specialized agent to use for this task"),
-  task_id: z
-    .string()
-    .describe(
+export const Parameters = Schema.Struct({
+  description: Schema.String.annotate({ description: "A short (3-5 words) description of the task" }),
+  prompt: Schema.String.annotate({ description: "The task for the agent to perform" }),
+  subagent_type: Schema.String.annotate({ description: "The type of specialized agent to use for this task" }),
+  task_id: Schema.optional(Schema.String).annotate({
+    description:
      "This should only be set if you mean to resume a previous task (you can pass a prior task_id and the task will continue the same subagent session as before instead of creating a fresh one)",
-    )
-    .optional(),
-  command: z.string().describe("The command that triggered this task").optional(),
+  }),
+  command: Schema.optional(Schema.String).annotate({ description: "The command that triggered this task" }),
 })

 export const TaskTool = Tool.define(
@@ -37,7 +34,7 @@ export const TaskTool = Tool.define(
    const config = yield* Config.Service
    const sessions = yield* Session.Service

-    const run = Effect.fn("TaskTool.execute")(function* (params: z.infer<typeof parameters>, ctx: Tool.Context) {
+    const run = Effect.fn("TaskTool.execute")(function* (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) {
      const cfg = yield* config.get()

      if (!ctx.extra?.bypassAgentCheck) {
@@ -168,8 +165,8 @@ export const TaskTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters,
-      execute: (params: z.infer<typeof parameters>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) => run(params, ctx).pipe(Effect.orDie),
    }
  }),
 )
--- a/packages/opencode/src/tool/todo.ts
+++ b/packages/opencode/src/tool/todo.ts
@@ -1,39 +1,34 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import * as Tool from "./tool"
 import DESCRIPTION_WRITE from "./todowrite.txt"
 import { Todo } from "../session/todo"

-// Parameters are kept inline rather than derived from Todo.Info because
-// Tool.define requires z.ZodObject-typed parameters for execute() inference,
-// and zodObject(Todo.Info) returns ZodObject<any> — reaching into .shape would
-// erase field types. Tool schemas migrate to Effect Schema as a separate slice
-// per specs/effect/schema.md.
-const parameters = z.object({
-  todos: z
-    .array(
-      z.object({
-        content: z.string().describe("Brief description of the task"),
-        status: z.string().describe("Current status of the task: pending, in_progress, completed, cancelled"),
-        priority: z.string().describe("Priority level of the task: high, medium, low"),
-      }),
-    )
-    .describe("The updated todo list"),
+// Todo.Info is still a zod schema (session/todo.ts). Inline the field shape
+// here rather than referencing its `.shape` — the LLM-visible JSON Schema is
+// identical, and it removes the last zod dependency from this tool.
+const TodoItem = Schema.Struct({
+  content: Schema.String.annotate({ description: "Brief description of the task" }),
+  status: Schema.String.annotate({ description: "Current status of the task: pending, in_progress, completed, cancelled" }),
+  priority: Schema.String.annotate({ description: "Priority level of the task: high, medium, low" }),
+})
+
+export const Parameters = Schema.Struct({
+  todos: Schema.mutable(Schema.Array(TodoItem)).annotate({ description: "The updated todo list" }),
 })

 type Metadata = {
  todos: Todo.Info[]
 }

-export const TodoWriteTool = Tool.define<typeof parameters, Metadata, Todo.Service>(
+export const TodoWriteTool = Tool.define<typeof Parameters, Metadata, Todo.Service>(
  "todowrite",
  Effect.gen(function* () {
    const todo = yield* Todo.Service

    return {
      description: DESCRIPTION_WRITE,
-      parameters,
-      execute: (params: z.infer<typeof parameters>, ctx: Tool.Context<Metadata>) =>
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context<Metadata>) =>
        Effect.gen(function* () {
          yield* ctx.ask({
            permission: "todowrite",
@@ -55,6 +50,6 @@ export const TodoWriteTool = Tool.define<typeof parameters, Metadata, Todo.Servi
            },
          }
        }),
-    } satisfies Tool.DefWithoutID<typeof parameters, Metadata>
+    } satisfies Tool.DefWithoutID<typeof Parameters, Metadata>
  }),
 )
--- a/packages/opencode/src/tool/tool.ts
+++ b/packages/opencode/src/tool/tool.ts
@@ -1,5 +1,4 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import type { MessageV2 } from "../session/message-v2"
 import type { Permission } from "../permission"
 import type { SessionID, MessageID } from "../session/schema"
@@ -32,29 +31,33 @@ export interface ExecuteResult<M extends Metadata = Metadata> {
  attachments?: Omit<MessageV2.FilePart, "id" | "sessionID" | "messageID">[]
 }

-export interface Def<Parameters extends z.ZodType = z.ZodType, M extends Metadata = Metadata> {
+export interface Def<Parameters extends Schema.Decoder<unknown> = Schema.Decoder<unknown>, M extends Metadata = Metadata> {
  id: string
  description: string
  parameters: Parameters
-  execute(args: z.infer<Parameters>, ctx: Context): Effect.Effect<ExecuteResult<M>>
-  formatValidationError?(error: z.ZodError): string
+  execute(args: Schema.Schema.Type<Parameters>, ctx: Context): Effect.Effect<ExecuteResult<M>>
+  formatValidationError?(error: unknown): string
 }
-export type DefWithoutID<Parameters extends z.ZodType = z.ZodType, M extends Metadata = Metadata> = Omit<
+export type DefWithoutID<Parameters extends Schema.Decoder<unknown> = Schema.Decoder<unknown>, M extends Metadata = Metadata> = Omit<
  Def<Parameters, M>,
  "id"
 >

-export interface Info<Parameters extends z.ZodType = z.ZodType, M extends Metadata = Metadata> {
+export interface Info<Parameters extends Schema.Decoder<unknown> = Schema.Decoder<unknown>, M extends Metadata = Metadata> {
  id: string
  init: () => Effect.Effect<DefWithoutID<Parameters, M>>
 }

-type Init<Parameters extends z.ZodType, M extends Metadata> =
+type Init<Parameters extends Schema.Decoder<unknown>, M extends Metadata> =
  | DefWithoutID<Parameters, M>
  | (() => Effect.Effect<DefWithoutID<Parameters, M>>)

 export type InferParameters<T> =
-  T extends Info<infer P, any> ? z.infer<P> : T extends Effect.Effect<Info<infer P, any>, any, any> ? z.infer<P> : never
+  T extends Info<infer P, any>
+    ? Schema.Schema.Type<P>
+    : T extends Effect.Effect<Info<infer P, any>, any, any>
+      ? Schema.Schema.Type<P>
+      : never
 export type InferMetadata<T> =
  T extends Info<any, infer M> ? M : T extends Effect.Effect<Info<any, infer M>, any, any> ? M : never

@@ -65,7 +68,7 @@ export type InferDef<T> =
      ? Def<P, M>
      : never

-function wrap<Parameters extends z.ZodType, Result extends Metadata>(
+function wrap<Parameters extends Schema.Decoder<unknown>, Result extends Metadata>(
  id: string,
  init: Init<Parameters, Result>,
  truncate: Truncate.Interface,
@@ -74,6 +77,10 @@ function wrap<Parameters extends z.ZodType, Result extends Metadata>(
  return () =>
    Effect.gen(function* () {
      const toolInfo = typeof init === "function" ? { ...(yield* init()) } : { ...init }
+      // Compile the parser closure once per tool init; `decodeUnknownEffect`
+      // allocates a new closure per call, so hoisting avoids re-closing it for
+      // every LLM tool invocation.
+      const decode = Schema.decodeUnknownEffect(toolInfo.parameters)
      const execute = toolInfo.execute
      toolInfo.execute = (args, ctx) => {
        const attrs = {
@@ -83,19 +90,17 @@ function wrap<Parameters extends z.ZodType, Result extends Metadata>(
          ...(ctx.callID ? { "tool.call_id": ctx.callID } : {}),
        }
        return Effect.gen(function* () {
-          yield* Effect.try({
-            try: () => toolInfo.parameters.parse(args),
-            catch: (error) => {
-              if (error instanceof z.ZodError && toolInfo.formatValidationError) {
-                return new Error(toolInfo.formatValidationError(error), { cause: error })
-              }
-              return new Error(
-                `The ${id} tool was called with invalid arguments: ${error}.\nPlease rewrite the input so it satisfies the expected schema.`,
-                { cause: error },
-              )
-            },
-          })
-          const result = yield* execute(args, ctx)
+          const decoded = yield* decode(args).pipe(
+            Effect.mapError((error) =>
+              toolInfo.formatValidationError
+                ? new Error(toolInfo.formatValidationError(error), { cause: error })
+                : new Error(
+                    `The ${id} tool was called with invalid arguments: ${error}.\nPlease rewrite the input so it satisfies the expected schema.`,
+                    { cause: error },
+                  ),
+            ),
+          )
+          const result = yield* execute(decoded as Schema.Schema.Type<Parameters>, ctx)
          if (result.metadata.truncated !== undefined) {
            return result
          }
@@ -116,7 +121,7 @@ function wrap<Parameters extends z.ZodType, Result extends Metadata>(
    })
 }

-export function define<Parameters extends z.ZodType, Result extends Metadata, R, ID extends string = string>(
+export function define<Parameters extends Schema.Decoder<unknown>, Result extends Metadata, R, ID extends string = string>(
  id: ID,
  init: Effect.Effect<Init<Parameters, Result>, never, R>,
 ): Effect.Effect<Info<Parameters, Result>, never, R | Truncate.Service | Agent.Service> & { id: ID } {
@@ -131,7 +136,7 @@ export function define<Parameters extends z.ZodType, Result extends Metadata, R,
  )
 }

-export function init<P extends z.ZodType, M extends Metadata>(info: Info<P, M>): Effect.Effect<Def<P, M>> {
+export function init<P extends Schema.Decoder<unknown>, M extends Metadata>(info: Info<P, M>): Effect.Effect<Def<P, M>> {
  return Effect.gen(function* () {
    const init = yield* info.init()
    return {
--- a/packages/opencode/src/tool/webfetch.ts
+++ b/packages/opencode/src/tool/webfetch.ts
@@ -1,5 +1,4 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import { HttpClient, HttpClientRequest } from "effect/unstable/http"
 import * as Tool from "./tool"
 import TurndownService from "turndown"
@@ -10,13 +9,14 @@ const MAX_RESPONSE_SIZE = 5 * 1024 * 1024 // 5MB
 const DEFAULT_TIMEOUT = 30 * 1000 // 30 seconds
 const MAX_TIMEOUT = 120 * 1000 // 2 minutes

-const parameters = z.object({
-  url: z.string().describe("The URL to fetch content from"),
-  format: z
-    .enum(["text", "markdown", "html"])
-    .default("markdown")
-    .describe("The format to return the content in (text, markdown, or html). Defaults to markdown."),
-  timeout: z.number().describe("Optional timeout in seconds (max 120)").optional(),
+export const Parameters = Schema.Struct({
+  url: Schema.String.annotate({ description: "The URL to fetch content from" }),
+  format: Schema.Literals(["text", "markdown", "html"])
+    .pipe(Schema.optional, Schema.withDecodingDefault(Effect.succeed("markdown" as const)))
+    .annotate({
+      description: "The format to return the content in (text, markdown, or html). Defaults to markdown.",
+    }),
+  timeout: Schema.optional(Schema.Number).annotate({ description: "Optional timeout in seconds (max 120)" }),
 })

 export const WebFetchTool = Tool.define(
@@ -27,8 +27,8 @@ export const WebFetchTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters,
-      execute: (params: z.infer<typeof parameters>, ctx: Tool.Context) =>
+      parameters: Parameters,
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) =>
        Effect.gen(function* () {
          if (!params.url.startsWith("http://") && !params.url.startsWith("https://")) {
            throw new Error("URL must start with http:// or https://")
--- a/packages/opencode/src/tool/websearch.ts
+++ b/packages/opencode/src/tool/websearch.ts
@@ -1,27 +1,24 @@
-import z from "zod"
-import { Effect } from "effect"
+import { Effect, Schema } from "effect"
 import { HttpClient } from "effect/unstable/http"
 import * as Tool from "./tool"
 import * as McpExa from "./mcp-exa"
 import DESCRIPTION from "./websearch.txt"

-const Parameters = z.object({
-  query: z.string().describe("Websearch query"),
-  numResults: z.number().optional().describe("Number of search results to return (default: 8)"),
-  livecrawl: z
-    .enum(["fallback", "preferred"])
-    .optional()
-    .describe(
+export const Parameters = Schema.Struct({
+  query: Schema.String.annotate({ description: "Websearch query" }),
+  numResults: Schema.optional(Schema.Number).annotate({
+    description: "Number of search results to return (default: 8)",
+  }),
+  livecrawl: Schema.optional(Schema.Literals(["fallback", "preferred"])).annotate({
+    description:
      "Live crawl mode - 'fallback': use live crawling as backup if cached content unavailable, 'preferred': prioritize live crawling (default: 'fallback')",
-    ),
-  type: z
-    .enum(["auto", "fast", "deep"])
-    .optional()
-    .describe("Search type - 'auto': balanced search (default), 'fast': quick results, 'deep': comprehensive search"),
-  contextMaxCharacters: z
-    .number()
-    .optional()
-    .describe("Maximum characters for context string optimized for LLMs (default: 10000)"),
+  }),
+  type: Schema.optional(Schema.Literals(["auto", "fast", "deep"])).annotate({
+    description: "Search type - 'auto': balanced search (default), 'fast': quick results, 'deep': comprehensive search",
+  }),
+  contextMaxCharacters: Schema.optional(Schema.Number).annotate({
+    description: "Maximum characters for context string optimized for LLMs (default: 10000)",
+  }),
 })

 export const WebSearchTool = Tool.define(
@@ -34,7 +31,7 @@ export const WebSearchTool = Tool.define(
        return DESCRIPTION.replace("{{year}}", new Date().getFullYear().toString())
      },
      parameters: Parameters,
-      execute: (params: z.infer<typeof Parameters>, ctx: Tool.Context) =>
+      execute: (params: Schema.Schema.Type<typeof Parameters>, ctx: Tool.Context) =>
        Effect.gen(function* () {
          yield* ctx.ask({
            permission: "websearch",
--- a/packages/opencode/src/tool/write.ts
+++ b/packages/opencode/src/tool/write.ts
@@ -1,4 +1,4 @@
-import z from "zod"
+import { Schema } from "effect"
 import * as path from "path"
 import { Effect } from "effect"
 import * as Tool from "./tool"
@@ -17,6 +17,13 @@ import * as Bom from "@/util/bom"

 const MAX_PROJECT_DIAGNOSTICS_FILES = 5

+export const Parameters = Schema.Struct({
+  content: Schema.String.annotate({ description: "The content to write to the file" }),
+  filePath: Schema.String.annotate({
+    description: "The absolute path to the file to write (must be absolute, not relative)",
+  }),
+})
+
 export const WriteTool = Tool.define(
  "write",
  Effect.gen(function* () {
@@ -27,10 +34,7 @@ export const WriteTool = Tool.define(

    return {
      description: DESCRIPTION,
-      parameters: z.object({
-        content: z.string().describe("The content to write to the file"),
-        filePath: z.string().describe("The absolute path to the file to write (must be absolute, not relative)"),
-      }),
+      parameters: Parameters,
      execute: (params: { content: string; filePath: string }, ctx: Tool.Context) =>
        Effect.gen(function* () {
          const filepath = path.isAbsolute(params.filePath)