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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.

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Error Reference

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ElicitationNotSupportedError

Thrown when attempting to elicit from a client that does not support elicitation or when the transport is unavailable.
PropertyTypeValue
codestringELICITATION_NOT_SUPPORTED
statusCodenumber400
isPublicbooleantrue
new ElicitationNotSupportedError(message?: string)
Example: 
import { ElicitationNotSupportedError } from '@frontmcp/sdk';

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

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ElicitationTimeoutError

Thrown when an elicitation request times out waiting for the user’s response.
PropertyTypeValue
codestringELICITATION_TIMEOUT
statusCodenumber408
isPublicbooleantrue
elicitIdstringThe timed-out request ID
ttlnumberThe 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)."

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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.
PropertyTypeValue
codestringELICITATION_FALLBACK
statusCodenumber200
isPublicbooleantrue
elicitIdstringUnique elicitation request ID
elicitMessagestringMessage to display to user
schemaRecord<string, unknown>JSON Schema for expected response
toolNamestringTool that requested elicitation
toolInputunknownOriginal tool input args
ttlnumberTime-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.

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ElicitationStoreNotInitializedError

Thrown when attempting to access the elicitation store before scope initialization has completed. Callers should await scope.ready before accessing elicitationStore.
PropertyTypeValue
codestringELICITATION_STORE_NOT_INITIALIZED
statusCodenumber500
isPublicbooleanfalse
new ElicitationStoreNotInitializedError()

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ElicitationDisabledError

Thrown when elicitation is used but disabled in server configuration. Enable via @FrontMcp({ elicitation: { enabled: true } }).
PropertyTypeValue
codestringELICITATION_DISABLED
statusCodenumber400
isPublicbooleantrue
new ElicitationDisabledError()
The internal message includes configuration guidance. The public message is: "Elicitation is disabled on this server."

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ElicitationEncryptionError

Thrown when encryption or decryption of elicitation data fails — typically when the session ID is missing or key derivation fails.
PropertyTypeValue
codestringELICITATION_ENCRYPTION_ERROR
statusCodenumber500
isPublicbooleanfalse
originalErrorError | undefinedThe underlying cause
new ElicitationEncryptionError(message: string, originalError?: Error)

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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).
PropertyTypeValue
codestringELICITATION_SUBSCRIPTION_ERROR
statusCodenumber500
isPublicbooleanfalse
elicitIdstringThe elicitation request ID
originalErrorError | undefinedThe underlying cause
new ElicitationSubscriptionError(elicitId: string, originalError?: Error)