Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnly/idempotent/destructive annotations, the description discloses that the signature is NOT verified and that the response explicitly says so. It also warns not to treat decoded values as proof, adding critical behavioral context about limitations and security implications.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise, front-loaded with the core function, and uses three sentences to cover what it does, the security caveat, and usage guidance. Every sentence adds value with no fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple parameter set, comprehensive annotations, and existence of an output schema, the description covers all necessary context: function, usage limitations, and security warning. It is complete for an agent to correctly select and invoke the tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema covers 100% of parameters with a single 'token' parameter described as 'The JWT string,' which is self-explanatory. The description does not add extra parameter semantics, but the schema already fully documents it, so baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool decodes the header and payload of a JWT and reports issued-at/expiry timestamps plus seconds remaining. This specific verb+resource pair distinguishes it from all sibling tools, none of which handle JWT decoding.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use the tool ('debugging a token you already hold') and warns against using it for verification, noting that verification requires the secret and belongs in your own service. This provides clear usage context and exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.