MCP TypeScript SDK (V2) / @modelcontextprotocol/server / server/legacyInputRequiredShim

server/legacyInputRequiredShim

Classes

LegacyInputRequiredShim

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:160

The fulfilment loop — see the module doc for the contract.

Constructors

Constructor

new LegacyInputRequiredShim(_host): LegacyInputRequiredShim

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:161

Parameters

_host

LegacyInputRequiredShimHost

Returns

LegacyInputRequiredShim

Methods

fulfill()

fulfill(method, handler, request, ctx, firstResult): Promise<{[key: string]: unknown; _meta?: {[key: string]: unknown; io.modelcontextprotocol/serverInfo?: { description?: string; icons?: object[]; name: string; title?: string; version: string; websiteUrl?: string; }; }; }>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:163

Parameters

method

string

handler

(request, ctx) => Promise<{[key: string]: unknown; _meta?: {[key: string]: unknown; io.modelcontextprotocol/serverInfo?: { description?: string; icons?: object[]; name: string; title?: string; version: string; websiteUrl?: string; }; }; }>

request

id

string | number = RequestIdSchema

jsonrpc

"2.0" = ...

method

string = ...

params?

{[key: string]: unknown; _meta?: {[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; }; } = ...

params._meta?

{[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; } = ...

See General fields: _meta for notes on _meta usage.

{ taskId: string; } = ...

If specified, this request is related to the provided task.

string = ...

params._meta.progressToken?

string | number = ...

If specified, the caller is requesting out-of-band progress notifications for this request (as represented by notifications/progress). The value of this parameter is an opaque token that will be attached to any subsequent notifications. The receiver is not obligated to provide these notifications.

ctx

ServerContext

firstResult

_meta?

{[key: string]: unknown; io.modelcontextprotocol/serverInfo?: { description?: string; icons?: object[]; name: string; title?: string; version: string; websiteUrl?: string; }; } = ...

See MCP specification for notes on _meta usage.

_meta.io.modelcontextprotocol/serverInfo?

{ description?: string; icons?: object[]; name: string; title?: string; version: string; websiteUrl?: string; }

_meta.io.modelcontextprotocol/serverInfo.description?

string = ...

An optional human-readable description of what this implementation does.

This can be used by clients or servers to provide context about their purpose and capabilities. For example, a server might describe the types of resources or tools it provides, while a client might describe its intended use case.

_meta.io.modelcontextprotocol/serverInfo.icons?

object[] = ...

Optional set of sized icons that the client can display in a user interface.

Clients that support rendering icons MUST support at least the following MIME types:

image/png - PNG images (safe, universal compatibility)
image/jpeg (and image/jpg) - JPEG images (safe, universal compatibility)

Clients that support rendering icons SHOULD also support:

image/svg+xml - SVG images (scalable but requires security precautions)
image/webp - WebP images (modern, efficient format)

_meta.io.modelcontextprotocol/serverInfo.name

string = ...

Intended for programmatic or logical use, but used as a display name in past specs or fallback

_meta.io.modelcontextprotocol/serverInfo.title?

string = ...

Intended for UI and end-user contexts — optimized to be human-readable and easily understood, even by those unfamiliar with domain-specific terminology.

If not provided, the name should be used for display (except for Tool, where annotations.title should be given precedence over using name, if present).

_meta.io.modelcontextprotocol/serverInfo.version

string = ...

_meta.io.modelcontextprotocol/serverInfo.websiteUrl?

string = ...

An optional URL of the website for this implementation.

Returns

Promise<{[key: string]: unknown; _meta?: {[key: string]: unknown; io.modelcontextprotocol/serverInfo?: { description?: string; icons?: object[]; name: string; title?: string; version: string; websiteUrl?: string; }; }; }>

Interfaces

CoercedEmbeddedInputRequest

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:81

A coerced inputRequests entry: the kind-narrowed embedded request.

Properties

method

method: EmbeddedInputRequestMethod

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:82

params?

optional params?: Record<string, unknown>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:83

LegacyInputRequiredShimHost

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:149

Everything the shim needs from Server: the knobs, the per-request resolved capability view (initialize state on sessionful legacy; empty on per-request stateless instances), the requestState verify runner (deny-on-error → the frozen -32602), and the 2025-era senders. The shim's own gate is authoritative; elicitation accepted content passes through UNVALIDATED for parity with the modern client driver.

Properties

maxRounds

readonly maxRounds: number

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:150

roundTimeoutMs

readonly roundTimeoutMs: number

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:151

Methods

listRoots()

listRoots(params, options): Promise<unknown>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:156

Parameters

params

Record<string, unknown> | undefined

options

RequestOptions

Returns

Promise<unknown>

resolvedClientCapabilities()

resolvedClientCapabilities(ctx): { elicitation?: {[key: string]: string | number | boolean | {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; form?: {[key: string]: string | number | boolean | {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; applyDefaults?: boolean; }; url?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; }; experimental?: {[key: string]: object; }; extensions?: {[key: string]: object; }; roots?: { listChanged?: boolean; }; sampling?: { context?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; tools?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; }; tasks?: {[key: string]: unknown; cancel?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; list?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; requests?: {[key: string]: unknown; elicitation?: {[key: string]: unknown; create?: {[key: string]: ... | ... | ... | ... | ... | ... | ...; }; }; sampling?: {[key: string]: unknown; createMessage?: {[key: string]: ... | ... | ... | ... | ... | ... | ...; }; }; }; }; } | undefined

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:152

Parameters

ctx

ServerContext

Returns

Type Literal

{ elicitation?: {[key: string]: string | number | boolean | {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; form?: {[key: string]: string | number | boolean | {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; applyDefaults?: boolean; }; url?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; }; experimental?: {[key: string]: object; }; extensions?: {[key: string]: object; }; roots?: { listChanged?: boolean; }; sampling?: { context?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; tools?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; }; tasks?: {[key: string]: unknown; cancel?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; list?: {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; }; requests?: {[key: string]: unknown; elicitation?: {[key: string]: unknown; create?: {[key: string]: ... | ... | ... | ... | ... | ... | ...; }; }; sampling?: {[key: string]: unknown; createMessage?: {[key: string]: ... | ... | ... | ... | ... | ... | ...; }; }; }; }; }

elicitation?

optional elicitation?: object

Present if the client supports eliciting user input.

Index Signature

[key: string]: string | number | boolean | {[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null

elicitation.form?

optional form?: object

Index Signature

elicitation.form.applyDefaults?

optional applyDefaults?: boolean

elicitation.url?

optional url?: object

Index Signature

[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null

experimental?

optional experimental?: object

Experimental, non-standard capabilities that the client supports.

Index Signature

[key: string]: object

extensions?

optional extensions?: object

Extensions that the client supports. Keys are extension identifiers (vendor-prefix/extension-name).

Index Signature

[key: string]: object

roots?

optional roots?: object

Present if the client supports listing roots.

Deprecated

Deprecated as of protocol version 2026-07-28 (SEP-2577); remains in the specification for at least twelve months. Migrate to passing paths via tool parameters, resource URIs, or configuration.

roots.listChanged?

optional listChanged?: boolean

Whether the client supports issuing notifications for changes to the roots list.

sampling?

optional sampling?: object

Present if the client supports sampling from an LLM.

Deprecated

Deprecated as of protocol version 2026-07-28 (SEP-2577); remains in the specification for at least twelve months. Migrate to calling LLM provider APIs directly.

sampling.context?

optional context?: object

Present if the client supports context inclusion via includeContext parameter. If not declared, servers SHOULD only use includeContext: "none" (or omit it).

Index Signature

sampling.tools?

optional tools?: object

Present if the client supports tool use via tools and toolChoice parameters.

Index Signature

tasks?

optional tasks?: object

Present if the client supports task creation.

Index Signature

[key: string]: unknown

Deprecated

2025-11-25 wire vocabulary with no SDK runtime; parsed for interoperability only — servers built on this SDK never advertise it.

tasks.cancel?

optional cancel?: object

Present if the client supports cancelling tasks.

Index Signature

tasks.list?

optional list?: object

Present if the client supports listing tasks.

Index Signature

tasks.requests?

optional requests?: object

Capabilities for task creation on specific request types.

Index Signature

[key: string]: unknown

tasks.requests.elicitation?

optional elicitation?: object

Task support for elicitation requests.

Index Signature

[key: string]: unknown

tasks.requests.elicitation.create?

optional create?: object

Index Signature

[key: string]: ... | ... | ... | ... | ... | ... | ...

tasks.requests.sampling?

optional sampling?: object

Task support for sampling requests.

Index Signature

[key: string]: unknown

tasks.requests.sampling.createMessage?

optional createMessage?: object

Index Signature

[key: string]: ... | ... | ... | ... | ... | ... | ...

undefined

sendElicitation()

sendElicitation(params, options): Promise<unknown>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:154

Parameters

params

{ _meta?: {[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; }; message: string; mode?: "form"; requestedSchema: {[key: string]: unknown; properties: {[key: string]: { default?: boolean; description?: string; title?: string; type: "boolean"; } | { default?: string; description?: string; format?: "date" | "uri" | "email" | "date-time"; maxLength?: number; minLength?: number; title?: string; type: "string"; } | { default?: number; description?: string; maximum?: number; minimum?: number; title?: string; type: "number" | "integer"; } | { default?: string; description?: string; enum: string[]; enumNames?: string[]; title?: string; type: "string"; } | { default?: string; description?: string; enum: string[]; title?: string; type: "string"; } | { default?: string; description?: string; oneOf: object[]; title?: string; type: "string"; } | { default?: string[]; description?: string; items: { enum: string[]; type: "string"; }; maxItems?: number; minItems?: number; title?: string; type: "array"; } | { default?: string[]; description?: string; items: { anyOf: object[]; }; maxItems?: number; minItems?: number; title?: string; type: "array"; }; }; required?: string[]; type: "object"; }; task?: { ttl?: number; }; } | { _meta?: {[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; }; elicitationId: string; message: string; mode: "url"; task?: { ttl?: number; }; url: string; }

Type Literal

_meta?

{[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; } = ...

See General fields: _meta for notes on _meta usage.

{ taskId: string; } = ...

If specified, this request is related to the provided task.

string = ...

_meta.progressToken?

string | number = ...

message

string = ...

The message to present to the user describing what information is being requested.

mode?

"form" = ...

The elicitation mode.

Optional for backward compatibility. Clients MUST treat missing mode as "form".

requestedSchema

{[key: string]: unknown; properties: {[key: string]: { default?: boolean; description?: string; title?: string; type: "boolean"; } | { default?: string; description?: string; format?: "date" | "uri" | "email" | "date-time"; maxLength?: number; minLength?: number; title?: string; type: "string"; } | { default?: number; description?: string; maximum?: number; minimum?: number; title?: string; type: "number" | "integer"; } | { default?: string; description?: string; enum: string[]; enumNames?: string[]; title?: string; type: "string"; } | { default?: string; description?: string; enum: string[]; title?: string; type: "string"; } | { default?: string; description?: string; oneOf: object[]; title?: string; type: "string"; } | { default?: string[]; description?: string; items: { enum: string[]; type: "string"; }; maxItems?: number; minItems?: number; title?: string; type: "array"; } | { default?: string[]; description?: string; items: { anyOf: object[]; }; maxItems?: number; minItems?: number; title?: string; type: "array"; }; }; required?: string[]; type: "object"; } = ...

A restricted subset of JSON Schema. Only top-level properties are allowed, without nesting.

requestedSchema.properties

{[key: string]: { default?: boolean; description?: string; title?: string; type: "boolean"; } | { default?: string; description?: string; format?: "date" | "uri" | "email" | "date-time"; maxLength?: number; minLength?: number; title?: string; type: "string"; } | { default?: number; description?: string; maximum?: number; minimum?: number; title?: string; type: "number" | "integer"; } | { default?: string; description?: string; enum: string[]; enumNames?: string[]; title?: string; type: "string"; } | { default?: string; description?: string; enum: string[]; title?: string; type: "string"; } | { default?: string; description?: string; oneOf: object[]; title?: string; type: "string"; } | { default?: string[]; description?: string; items: { enum: string[]; type: "string"; }; maxItems?: number; minItems?: number; title?: string; type: "array"; } | { default?: string[]; description?: string; items: { anyOf: object[]; }; maxItems?: number; minItems?: number; title?: string; type: "array"; }; } = ...

requestedSchema.required?

string[] = ...

requestedSchema.type

"object" = ...

task?

{ ttl?: number; } = ...

If specified, the caller is requesting task-augmented execution for this request. The request will return a CreateTaskResult immediately, and the actual result can be retrieved later via tasks/result.

Task augmentation is subject to capability negotiation - receivers MUST declare support for task augmentation of specific request types in their capabilities.

task.ttl?

number = ...

Type Literal

{ _meta?: {[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; }; elicitationId: string; message: string; mode: "url"; task?: { ttl?: number; }; url: string; }

_meta?

{[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; } = ...

See General fields: _meta for notes on _meta usage.

{ taskId: string; } = ...

If specified, this request is related to the provided task.

string = ...

_meta.progressToken?

string | number = ...

elicitationId

string = ...

The ID of the elicitation, which must be unique within the context of the server. The client MUST treat this ID as an opaque value.

Deprecated

Removed from the spec by #2891 (2026-07-28). The client learns the outcome of an out-of-band interaction by retrying the original request; no server-initiated completion signal exists in the 2026-07-28 revision. Kept here for the 2025-era URL-mode flow only.

message

string = ...

The message to present to the user explaining why the interaction is needed.

mode

"url" = ...

The elicitation mode.

task?

{ ttl?: number; } = ...

Task augmentation is subject to capability negotiation - receivers MUST declare support for task augmentation of specific request types in their capabilities.

task.ttl?

number = ...

url

string = ...

The URL that the user should navigate to.

options

RequestOptions

Returns

Promise<unknown>

sendSampling()

sendSampling(params, options): Promise<unknown>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:155

Parameters

params

_meta?

{[key: string]: unknown; io.modelcontextprotocol/related-task?: { taskId: string; }; progressToken?: string | number; } = ...

See General fields: _meta for notes on _meta usage.

{ taskId: string; } = ...

If specified, this request is related to the provided task.

string = ...

_meta.progressToken?

string | number = ...

includeContext?

"none" | "thisServer" | "allServers" = ...

A request to include context from one or more MCP servers (including the caller), to be attached to the prompt. The client MAY ignore this request.

Default is "none". The values "thisServer" and "allServers" are deprecated (SEP-2596): servers SHOULD omit this field or use "none", and SHOULD only use the deprecated values if the client declares ClientCapabilities.sampling.context.

Deprecated

The "thisServer" and "allServers" values are deprecated as of protocol version 2025-11-25 (SEP-2596) and will be removed no later than the Sampling feature itself (SEP-2577). Omit this field or use "none".

maxTokens

number = ...

The requested maximum number of tokens to sample (to prevent runaway completions).

The client MAY choose to sample fewer tokens than the requested maximum.

messages

object[] = ...

metadata?

{[key: string]: string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null)[] | null; } | string | number | boolean | { [x: string]: string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | number | boolean | ... | (string | ... 4 more ... | null)[] | null)[] | null)[] | null)[] | null; } | (string | ... 4 more ... | null)[] | null[] | null; } = ...

Optional metadata to pass through to the LLM provider. The format of this metadata is provider-specific.

modelPreferences?

{ costPriority?: number; hints?: object[]; intelligencePriority?: number; speedPriority?: number; } = ...

The server's preferences for which model to select. The client MAY modify or omit this request.

modelPreferences.costPriority?

number = ...

How much to prioritize cost when selecting a model.

modelPreferences.hints?

object[] = ...

Optional hints to use for model selection.

modelPreferences.intelligencePriority?

number = ...

How much to prioritize intelligence and capabilities when selecting a model.

modelPreferences.speedPriority?

number = ...

How much to prioritize sampling speed (latency) when selecting a model.

stopSequences?

string[] = ...

systemPrompt?

string = ...

An optional system prompt the server wants to use for sampling. The client MAY modify or omit this prompt.

task?

{ ttl?: number; } = ...

Task augmentation is subject to capability negotiation - receivers MUST declare support for task augmentation of specific request types in their capabilities.

task.ttl?

number = ...

temperature?

number = ...

toolChoice?

{ mode?: "required" | "auto" | "none"; } = ...

Controls how the model uses tools. The client MUST return an error if this field is provided but ClientCapabilities.sampling.tools is not declared. Default is { mode: "auto" }.

toolChoice.mode?

"required" | "auto" | "none" = ...

Controls when tools are used:

"auto": Model decides whether to use tools (default)
"required": Model MUST use at least one tool before completing
"none": Model MUST NOT use any tools

tools?

object[] = ...

Tools that the model may use during generation. The client MUST return an error if this field is provided but ClientCapabilities.sampling.tools is not declared.

options

RequestOptions

Returns

Promise<unknown>

verifyRequestState()

verifyRequestState(state, ctx, method): Promise<unknown>

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:153

Parameters

state

string

ctx

ServerContext

method

string

Returns

Promise<unknown>

ResolvedLegacyShimOptions

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:54

The ServerOptions.inputRequired bag with defaults applied.

Properties

legacyShim

legacyShim: boolean

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:57

maxRounds

maxRounds: number

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:55

roundTimeoutMs

roundTimeoutMs: number

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:56

Type Aliases

EmbeddedInputRequestMethod

EmbeddedInputRequestMethod = "elicitation/create" | "sampling/createMessage" | "roots/list"

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:78

The embedded input-request kinds the 2026-07-28 revision defines.

Functions

coerceEmbeddedInputRequest()

coerceEmbeddedInputRequest(method, key, entry): object

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:91

Validates one inputRequests entry: malformed or unknown kinds are server bugs and fail loudly on both eras. Shared by the modern seam's capability check and the shim's gate.

Parameters

method

string

key

string

entry

unknown

Returns

object

embedded

embedded: CoercedEmbeddedInputRequest

required

required: object

required.elicitation?

optional elicitation?: object

Present if the client supports eliciting user input.

Index Signature

required.elicitation.form?

optional form?: object

Index Signature

required.elicitation.form.applyDefaults?

optional applyDefaults?: boolean

required.elicitation.url?

optional url?: object

Index Signature

required.experimental?

optional experimental?: object

Experimental, non-standard capabilities that the client supports.

Index Signature

[key: string]: object

required.extensions?

optional extensions?: object

Extensions that the client supports. Keys are extension identifiers (vendor-prefix/extension-name).

Index Signature

[key: string]: object

required.roots?

optional roots?: object

Present if the client supports listing roots.

Deprecated

Deprecated as of protocol version 2026-07-28 (SEP-2577); remains in the specification for at least twelve months. Migrate to passing paths via tool parameters, resource URIs, or configuration.

required.roots.listChanged?

optional listChanged?: boolean

Whether the client supports issuing notifications for changes to the roots list.

required.sampling?

optional sampling?: object

Present if the client supports sampling from an LLM.

Deprecated

Deprecated as of protocol version 2026-07-28 (SEP-2577); remains in the specification for at least twelve months. Migrate to calling LLM provider APIs directly.

required.sampling.context?

optional context?: object

Present if the client supports context inclusion via includeContext parameter. If not declared, servers SHOULD only use includeContext: "none" (or omit it).

Index Signature

required.sampling.tools?

optional tools?: object

Present if the client supports tool use via tools and toolChoice parameters.

Index Signature

required.tasks?

optional tasks?: object

Present if the client supports task creation.

Index Signature

[key: string]: unknown

Deprecated

2025-11-25 wire vocabulary with no SDK runtime; parsed for interoperability only — servers built on this SDK never advertise it.

required.tasks.cancel?

optional cancel?: object

Present if the client supports cancelling tasks.

Index Signature

required.tasks.list?

optional list?: object

Present if the client supports listing tasks.

Index Signature

required.tasks.requests?

optional requests?: object

Capabilities for task creation on specific request types.

Index Signature

[key: string]: unknown

required.tasks.requests.elicitation?

optional elicitation?: object

Task support for elicitation requests.

Index Signature

[key: string]: unknown

required.tasks.requests.elicitation.create?

optional create?: object

Index Signature

[key: string]: ... | ... | ... | ... | ... | ... | ...

required.tasks.requests.sampling?

optional sampling?: object

Task support for sampling requests.

Index Signature

[key: string]: unknown

required.tasks.requests.sampling.createMessage?

optional createMessage?: object

Index Signature

[key: string]: ... | ... | ... | ... | ... | ... | ...

resolveLegacyShimOptions()

resolveLegacyShimOptions(options): ResolvedLegacyShimOptions

Defined in: packages/server/src/server/legacyInputRequiredShim.ts:61

Resolves and validates ServerOptions.inputRequired, failing loudly at construction time.

Parameters

options

{ legacyShim?: boolean; maxRounds?: number; roundTimeoutMs?: number; } | undefined

Returns

ResolvedLegacyShimOptions

index

Namespaces

migrations

v1-to-v2

mappings

transforms

index

Namespaces

middleware

auth

handlers

middleware

providers

sse

server/legacyInputRequiredShim ​

Classes ​

LegacyInputRequiredShim ​

Constructors ​

Constructor ​

Parameters ​

_host ​

Returns ​

Methods ​

fulfill() ​

Parameters ​

method ​

handler ​

request ​

id ​

jsonrpc ​

method ​

params? ​

params._meta? ​

params._meta.io.modelcontextprotocol/related-task? ​

params._meta.io.modelcontextprotocol/related-task.taskId ​

params._meta.progressToken? ​

ctx ​

firstResult ​

_meta? ​

_meta.io.modelcontextprotocol/serverInfo? ​

_meta.io.modelcontextprotocol/serverInfo.description? ​

_meta.io.modelcontextprotocol/serverInfo.icons? ​

_meta.io.modelcontextprotocol/serverInfo.name ​

_meta.io.modelcontextprotocol/serverInfo.title? ​

_meta.io.modelcontextprotocol/serverInfo.version ​

_meta.io.modelcontextprotocol/serverInfo.websiteUrl? ​

Returns ​

Interfaces ​

CoercedEmbeddedInputRequest ​

Properties ​

method ​

params? ​

LegacyInputRequiredShimHost ​

Properties ​

maxRounds ​

roundTimeoutMs ​

Methods ​

listRoots() ​

Parameters ​

params ​

options ​

Returns ​

resolvedClientCapabilities() ​

Parameters ​

ctx ​

Returns ​

Type Literal ​

elicitation? ​

Index Signature ​

elicitation.form? ​

Index Signature ​

elicitation.form.applyDefaults? ​

elicitation.url? ​

Index Signature ​

experimental? ​

Index Signature ​

extensions? ​

Index Signature ​

roots? ​

Deprecated ​

server/legacyInputRequiredShim

Classes

LegacyInputRequiredShim

Constructors

Constructor

Parameters

_host

Returns

Methods

fulfill()

Parameters

method

handler

request

id

jsonrpc

method

params?

params._meta?

params._meta.io.modelcontextprotocol/related-task?

params._meta.io.modelcontextprotocol/related-task.taskId

params._meta.progressToken?

ctx

firstResult

_meta?

_meta.io.modelcontextprotocol/serverInfo?

_meta.io.modelcontextprotocol/serverInfo.description?

_meta.io.modelcontextprotocol/serverInfo.icons?

_meta.io.modelcontextprotocol/serverInfo.name

_meta.io.modelcontextprotocol/serverInfo.title?

_meta.io.modelcontextprotocol/serverInfo.version

_meta.io.modelcontextprotocol/serverInfo.websiteUrl?

Returns

Interfaces

CoercedEmbeddedInputRequest

Properties

method

params?

LegacyInputRequiredShimHost

Properties

maxRounds

roundTimeoutMs

Methods

listRoots()

Parameters

params

options

Returns

resolvedClientCapabilities()

Parameters

ctx

Returns

Type Literal

elicitation?

Index Signature

elicitation.form?

Index Signature

elicitation.form.applyDefaults?

elicitation.url?

Index Signature

experimental?

Index Signature

extensions?

Index Signature

roots?

Deprecated

roots.listChanged?

sampling?

Deprecated

sampling.context?

Index Signature

sampling.tools?

Index Signature

tasks?

Index Signature

Deprecated

tasks.cancel?

Index Signature

tasks.list?

Index Signature