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

Goes well past the readOnlyHint/openWorldHint annotations by naming the exact warning conditions (alg none, missing/past exp, future nbf/iat, risky headers), declaring that nothing is verified, and disclosing the billing model including that schema-invalid input is rejected before charging.

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?

Front-loaded with the core action and its safety caveat, then the return shape, then billing. Every clause carries information an agent needs; nothing is redundant 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?

With no output schema, the description supplies the return shape and the semantics of the `verified: false` and `times.expired` fields, plus cost and rejection behavior. For a single-parameter read tool this is complete enough to invoke confidently.

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?

Only one parameter and schema description coverage is 100%, so the schema already carries the token format, length bounds and the 'do not send production tokens you cannot rotate' warning. The description adds no additional parameter-level meaning, which is the expected baseline here.

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?

States a specific verb and resource ('decodes a JWT header and payload') and immediately bounds the scope with 'without verifying it', which separates it from verification-oriented siblings like webhook-verify. An agent knows exactly what it gets and what it does not get.

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?

Usage is implied rather than stated: the tool is for inspecting tokens whose signatures you are not checking, and it flags risky claims. There is no explicit 'use this when / use X instead' routing against nearby siblings such as base64 (which can also decode a payload) or webhook-verify.

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