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)
import { ElicitationNotSupportedError } from '@frontmcp/sdk';
throw new ElicitationNotSupportedError('Client does not support elicitation');
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)
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()
"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)
