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

Annotations already declare readOnlyHint and idempotentHint, and the description adds a critical behavioral caveat: the signature is NOT verified, and the response explicitly says so. This goes beyond the structured annotations and gives essential security context.

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?

Two well-structured sentences: the first states the core function, the second provides vital security guidance. Every sentence earns its place, no filler.

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?

For a single-parameter, read-only tool with an output schema and strong annotations, the description fully covers purpose, usage boundaries, and the key caveat about signature verification. There are no meaningful gaps.

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 already provides 100% coverage with the parameter description 'The JWT string.' The description does not add significantly new semantic detail about the parameter itself, only restating that it is a JWT. 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 uses a specific verb 'Decodes' and clearly states the resource (JWT header/payload) and scope (reports issued-at/expiry as readable timestamps and seconds remaining). It distinguishes itself from sibling tools, none of which are JWT-specific.

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?

Explicitly states when to use: debugging a token you already hold, and when not to: never treat values as proof; verification needs the secret and belongs in your own service. This gives clear context and an alternative path.

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