🎯 Use case
This module implements the “MCPTool” tool (M C P) — something the model can call at runtime alongside other agent tools. On the API surface it exposes inputSchema, outputSchema, Output, and MCPTool — mainly functions, hooks, or classes. Dependencies touch schema validation. It composes internal code from Tool, utils, prompt, UI, and types (relative imports).
Generated from folder role, exports, dependency roots, and inline comments — not hand-reviewed for every path.
🧠 Inline summary
import { z } from 'zod/v4' import { buildTool, type ToolDef } from '../../Tool.js' import { lazySchema } from '../../utils/lazySchema.js' import type { PermissionResult } from '../../utils/permissions/PermissionResult.js' import { isOutputLineTruncated } from '../../utils/terminal.js'
📤 Exports (heuristic)
inputSchemaoutputSchemaOutputMCPTool
📚 External import roots
Package roots from from "…" (relative paths omitted).
zod
🖥️ Source preview
import { z } from 'zod/v4'
import { buildTool, type ToolDef } from '../../Tool.js'
import { lazySchema } from '../../utils/lazySchema.js'
import type { PermissionResult } from '../../utils/permissions/PermissionResult.js'
import { isOutputLineTruncated } from '../../utils/terminal.js'
import { DESCRIPTION, PROMPT } from './prompt.js'
import {
renderToolResultMessage,
renderToolUseMessage,
renderToolUseProgressMessage,
} from './UI.js'
// Allow any input object since MCP tools define their own schemas
export const inputSchema = lazySchema(() => z.object({}).passthrough())
type InputSchema = ReturnType<typeof inputSchema>
export const outputSchema = lazySchema(() =>
z.string().describe('MCP tool execution result'),
)
type OutputSchema = ReturnType<typeof outputSchema>
export type Output = z.infer<OutputSchema>
// Re-export MCPProgress from centralized types to break import cycles
export type { MCPProgress } from '../../types/tools.js'
export const MCPTool = buildTool({
isMcp: true,
// Overridden in mcpClient.ts with the real MCP tool name + args
isOpenWorld() {
return false
},
// Overridden in mcpClient.ts
name: 'mcp',
maxResultSizeChars: 100_000,
// Overridden in mcpClient.ts
async description() {
return DESCRIPTION
},
// Overridden in mcpClient.ts
async prompt() {
return PROMPT
},
get inputSchema(): InputSchema {
return inputSchema()
},
get outputSchema(): OutputSchema {
return outputSchema()
},
// Overridden in mcpClient.ts
async call() {
return {
data: '',
}
},
async checkPermissions(): Promise<PermissionResult> {
return {
behavior: 'passthrough',
message: 'MCPTool requires permission.',
}
},
renderToolUseMessage,
// Overridden in mcpClient.ts
userFacingName: () => 'mcp',
renderToolUseProgressMessage,
renderToolResultMessage,
isResultTruncated(output: Output): boolean {
return isOutputLineTruncated(output)
},
mapToolResultToToolResultBlockParam(content, toolUseID) {
return {
tool_use_id: toolUseID,
type: 'tool_result',
content,
}
},
} satisfies ToolDef<InputSchema, Output>)