Elicitation Errors

Overview

Elicitation errors are thrown during the MCP elicitation flow — the mechanism that allows tools to request additional user input during execution. These errors cover unsupported clients, timeouts, fallback flows, store initialization, encryption failures, and subscription issues.

Error Reference

ElicitationNotSupportedError

Thrown when attempting to elicit from a client that does not support elicitation or when the transport is unavailable.

Property	Type	Value
`code`	`string`	`ELICITATION_NOT_SUPPORTED`
`statusCode`	`number`	`400`
`isPublic`	`boolean`	`true`

new ElicitationNotSupportedError(message?: string)

Example:

import { ElicitationNotSupportedError } from '@frontmcp/sdk';

throw new ElicitationNotSupportedError('Client does not support elicitation');

The fallback also throws it for an anonymous caller without a verified session: no later sendElicitationResult call could be matched to that caller.

ElicitationNotOwnedError

Thrown by sendElicitationResult when the caller answering is not the one the elicitation was asked of. A pending fallback elicitation belongs to the session the server verified when the tool asked, or to the authenticated caller when there was no session. Mapped to JSON-RPC -32003.

Property	Type	Value
`code`	`string`	`ELICITATION_NOT_OWNED`
`statusCode`	`number`	`403`
`isPublic`	`boolean`	`true`
`elicitId`	`string`	The elicitation requested

new ElicitationNotOwnedError(elicitId: string)

ElicitationTimeoutError

Thrown when an elicitation request times out waiting for the user’s response.

Property	Type	Value
`code`	`string`	`ELICITATION_TIMEOUT`
`statusCode`	`number`	`408`
`isPublic`	`boolean`	`true`
`elicitId`	`string`	The timed-out request ID
`ttl`	`number`	The TTL that was exceeded (ms)

new ElicitationTimeoutError(elicitId: string, ttl: number)

Example:

import { ElicitationTimeoutError } from '@frontmcp/sdk';

throw new ElicitationTimeoutError('elicit_abc', 60000);
// Public: "Elicitation request timed out. The user did not respond within the allowed time (60 seconds)."

ElicitationFallbackRequired

Thrown when elicitation is requested but the client doesn’t support the standard protocol. This is not a failure — it triggers the fallback flow where the tool returns instructions to the LLM, and the LLM uses sendElicitationResult to continue.

Property	Type	Value
`code`	`string`	`ELICITATION_FALLBACK`
`statusCode`	`number`	`200`
`isPublic`	`boolean`	`true`
`elicitId`	`string`	Unique elicitation request ID
`elicitMessage`	`string`	Message to display to user
`schema`	`Record<string, unknown>`	JSON Schema for expected response
`toolName`	`string`	Tool that requested elicitation
`toolInput`	`unknown`	Original tool input args
`ttl`	`number`	Time-to-live (ms)

new ElicitationFallbackRequired(
  elicitId: string,
  elicitMessage: string,
  schema: Record<string, unknown>,
  toolName: string,
  toolInput: unknown,
  ttl: number,
)

This error has a statusCode of 200 because it is not a failure — it’s a signal to switch to the fallback elicitation flow.

ElicitationStoreNotInitializedError

Thrown when attempting to access the elicitation store before scope initialization has completed. Callers should await scope.ready before accessing elicitationStore.

Property	Type	Value
`code`	`string`	`ELICITATION_STORE_NOT_INITIALIZED`
`statusCode`	`number`	`500`
`isPublic`	`boolean`	`false`

new ElicitationStoreNotInitializedError()

ElicitationDisabledError

Thrown when elicitation is used but disabled in server configuration. Enable via @FrontMcp({ elicitation: { enabled: true } }).

Property	Type	Value
`code`	`string`	`ELICITATION_DISABLED`
`statusCode`	`number`	`400`
`isPublic`	`boolean`	`true`

new ElicitationDisabledError()

The internal message includes configuration guidance. The public message is: "Elicitation is disabled on this server."

ElicitationEncryptionError

Thrown when encryption or decryption of elicitation data fails — typically when the session ID is missing or key derivation fails.

Property	Type	Value
`code`	`string`	`ELICITATION_ENCRYPTION_ERROR`
`statusCode`	`number`	`500`
`isPublic`	`boolean`	`false`
`originalError`	`Error \| undefined`	The underlying cause

new ElicitationEncryptionError(message: string, originalError?: Error)

ElicitationSubscriptionError

Thrown when subscription to the elicitation pub/sub channel fails. This indicates a transport or infrastructure failure, not a user non-response (which would be a timeout).

Property	Type	Value
`code`	`string`	`ELICITATION_SUBSCRIPTION_ERROR`
`statusCode`	`number`	`500`
`isPublic`	`boolean`	`false`
`elicitId`	`string`	The elicitation request ID
`originalError`	`Error \| undefined`	The underlying cause

new ElicitationSubscriptionError(elicitId: string, originalError?: Error)

Decorators

API

Errors

Overview

Error Reference

ElicitationNotSupportedError

ElicitationNotOwnedError

ElicitationTimeoutError

ElicitationFallbackRequired

ElicitationStoreNotInitializedError

ElicitationDisabledError

ElicitationEncryptionError

ElicitationSubscriptionError

​Overview

​Error Reference

​ElicitationNotSupportedError

​ElicitationNotOwnedError

​ElicitationTimeoutError

​ElicitationFallbackRequired

​ElicitationStoreNotInitializedError

​ElicitationDisabledError

​ElicitationEncryptionError

​ElicitationSubscriptionError

Overview

Error Reference

ElicitationNotSupportedError

ElicitationNotOwnedError

ElicitationTimeoutError

ElicitationFallbackRequired

ElicitationStoreNotInitializedError

ElicitationDisabledError

ElicitationEncryptionError

ElicitationSubscriptionError