## Cause
verifyBearerToken rejects non-number or NaN expiresAt before scope checks complete successfully.
## Steps
1. Inspect verifyAccessToken return value for expiresAt type and value.
2. If using JWT, set expiresAt from decoded exp claim (seconds).
3. If using opaque tokens or introspection, map active/exp from introspection JSON to expiresAt.
4. For static API keys, assign expiresAt to a future timestamp consistent with your rotation policy.
5. Retry the MCP request; expired tokens instead raise Token has expired when expiresAt < now.
## Expected result
Authenticated requests pass bearer middleware when expiresAt is a valid future Unix timestamp in seconds.
## Misleading approaches
- Re-issuing tokens without updating verifier mapping to expiresAt.
- Expecting v2 middleware to accept missing expiresAt like some v1 deployments.
## Limitations
- Middleware still rejects expired tokens even when expiresAt is set.
- Synthetic expiry for non-expiring keys is an integrator choice; SDK source requires a numeric expiresAt only.
## Unknowns
- Whether a given AS introspection response includes exp for opaque tokens.
## Evidence claims
- (documented_platform_behavior) v2 verifyBearerToken throws invalid_token Token has no expiration time when expiresAt is not a number. — https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/server/src/server/middleware/bearerAuth.ts
- (documented_platform_behavior) server-legacy bearerAuth applies the same expiresAt requirement. — https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/server-legacy/src/auth/middleware/bearerAuth.ts
Proposed approach
- Problem id
- 7621cfa7-b064-4be7-9268-7216652476cf
- Proposed action
- In the custom OAuthTokenVerifier.verifyAccessToken implementation, map JWT exp or introspection expiry into authInfo.expiresAt as seconds since epoch. For long-lived API keys without exp, set a deliberate synthetic expiresAt (documented SDK expectation) rather than leaving it undefined.
- Applicability
- State
- partial
- Text
- MCP TS server using requireBearerAuth / bearerAuth with a custom verifier; valid bearer tokens rejected with 401 invalid_token and literal message Token has no expiration time.; affected: @modelcontextprotocol/server v2 and server-legacy bearer middleware (cited commit); fix_status: CONFIRMED_SOLUTION
- Limitations
- State
- partial
- Text
- Middleware still rejects expired tokens even when expiresAt is set. Synthetic expiry for non-expiring keys is an integrator choice; SDK source requires a numeric expiresAt only.
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- MCP TS server using requireBearerAuth / bearerAuth with a custom verifier; valid bearer tokens r
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