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ToolMetadata

Metadata interface for defining MCP tools.
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name
string
required
Unique identifier for the tool
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description
string
required
Human-readable description
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annotations
ToolAnnotations
Optional hints about tool behavior
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_meta
object
Metadata for the tool. Supports nested OpenAI metadata and other vendor extensions.
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_meta.openai
OpenAIMetadata
OpenAI-specific metadata for tool configuration
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_meta.ui
OpenAIMetadata
UI-specific metadata for tool rendering
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_meta[key]
unknown
Additional vendor-specific metadata extensions

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ToolAnnotations

Hints about tool behavior and characteristics.
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title
string
Human-readable title for the tool
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readOnlyHint
boolean
If true, the tool does not modify its environment
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destructiveHint
boolean
If true, the tool may perform destructive updates
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idempotentHint
boolean
If true, repeated calls with same args have no additional effect
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openWorldHint
boolean
If true, tool interacts with external entities
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[key]
any
Additional custom annotations

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ToolSchema

Type definition for tool input schemas. 
type ToolSchema = Record<string, CompatibleZodType>
A record mapping parameter names to Zod schema types. Supports both Zod v3 and v4 schemas.

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InferSchema

Utility type for inferring TypeScript types from tool schemas. 
type InferSchema<T extends Record<string, unknown>> = {
  [K in keyof T]: T[K] extends z.ZodTypeAny
    ? z.infer<T[K]>
    : T[K] extends ZodTypeV4<unknown>
      ? inferV4<T[K]>
      : never;
}
Automatically infers the TypeScript type from a ToolSchema definition, supporting both Zod v3 and v4 schemas.

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ToolExtraArguments

Extra arguments passed to MCP tool functions.
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signal
AbortSignal
required
An abort signal used to communicate if the request was cancelled from the sender’s side
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authInfo
object
Information about a validated access token, provided to request handlers
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authInfo.token
string
required
The access token
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authInfo.clientId
string
required
The client ID associated with this token
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authInfo.scopes
string[]
required
Scopes associated with this token
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authInfo.expiresAt
number
When the token expires (in seconds since epoch)
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authInfo.resource
URL
The RFC 8707 resource server identifier for which this token is valid
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authInfo.extra
Record<string, unknown>
Additional data associated with the token
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sessionId
string
The session ID from the transport, if available
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_meta
object
Metadata from the original request
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_meta.progressToken
string | number
Progress token for tracking long-running operations
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requestId
string | number
required
The JSON-RPC ID of the request being handled
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requestInfo
object
The original HTTP request information
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requestInfo.headers
Record<string, string | string[] | undefined>
required
The headers of the request
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sendNotification
(notification: any) => Promise<void>
required
Sends a notification that relates to the current request being handled
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sendRequest
function
required
Sends a request that relates to the current request being handledSignature:
<U extends z.ZodType<object>>(
  request: any,
  resultSchema: U,
  options?: {
    onprogress?: (progress: any) => void;
    signal?: AbortSignal;
    timeout?: number;
    resetTimeoutOnProgress?: boolean;
    maxTotalTimeout?: number;
    [key: string]: unknown;
  }
) => Promise<z.infer<U>>
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options.onprogress
(progress: any) => void
Progress notification callback
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options.signal
AbortSignal
Abort signal for cancelling the request
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options.timeout
number
Request timeout in milliseconds
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options.resetTimeoutOnProgress
boolean
Whether receiving progress notifications resets the timeout
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options.maxTotalTimeout
number
Maximum total time to wait for a response
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options[key]
unknown
Additional transport-specific options

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