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

With no annotations, the description carries the full burden. It does not say whether decoding is a purely local, read-only operation, whether the signature is validated, or how the tool behaves when a token is malformed or expired — only that expiry is reported.

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?

A single short sentence, front-loaded with the verb and resource and with zero filler. It is efficient, though it is under-specified rather than lean in the sense of having covered the essentials.

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 four-parameter tool with no annotations, no output schema, and no required-parameter declaration, the description is incomplete: it omits all parameter meaning, guarantees nothing about the return shape beyond naming three fields, and leaves the role of 'secret' unexplained.

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?

Schema description coverage is 0% and the description adds nothing about the four parameters. Worse, it offers no way to disambiguate the three apparent token-input aliases (jwt, input, token) or to explain why a decode operation takes a 'secret', which actively suggests signature verification behavior.

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 ('Decode a JWT token') plus the decoded artifacts returned (header, payload, expiry), which is more than a restatement of the name. It does not, however, differentiate itself from the sibling 'x402-jwt-verify', which an agent must choose between.

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?

No when-to-use or when-not-to-use guidance is given. The presence of a sibling jwt-verify tool makes the decode-vs-verify decision exactly the one an agent needs help with, and the description is silent on it.

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