MCP-CAC-004
ttlMs is a non-negative number
“ttlMs is a freshness hint (in milliseconds) allowing clients to cache responses.” — spec anchor
How to fix this
Make `ttlMs` a non-negative number of milliseconds. It is a freshness hint, so a negative or non-numeric value gives clients nothing to act on.
How the validator checks this
Probe P2.1, against a streamable-http server on the modern protocol. What it reports:
- pass
- Every ttlMs is a non-negative number
- fail
- ttlMs must be a non-negative number — got
Quoted from the probe that runs this check, so it cannot drift from what the validator actually reports.
This rule is checked deterministically: a fail here is a certain violation, not an inference.
Checked in the same request as MCP-HDR-008, MCP-HDR-009, MCP-RES-003, MCP-RES-006, MCP-RES-007, MCP-ERR-003, MCP-ERR-004, MCP-ERR-005, MCP-ERR-008, MCP-CAC-001, MCP-CAC-002, MCP-CAC-003, MCP-CAC-005, MCP-SCH-001, MCP-SCH-002, MCP-SCH-003, MCP-SCH-004, MCP-SCH-005, MCP-SCH-006, MCP-SCH-007, MCP-SEC-004, MCP-SEC-005, MCP-SEC-006, MCP-DEP-005.
Check your own server against this rule
The validator makes real protocol requests and reports this rule as pass, warn or fail alongside the other 78. Validate a server or read how the check works.
Other Caching metadata rules
- MCP-CAC-001ttlMs present on all five cacheable results
- MCP-CAC-002cacheScope present on all five cacheable results
- MCP-CAC-003cacheScope is exactly "public" or "private"
- MCP-CAC-005Authenticated or personalised results are not marked cacheScope: public