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

The description adds value beyond annotations by stating it is keyless, offline, and lists output specifics (header, payload, ISO date claims, expiration check). The annotation contradiction is false. It clearly describes behavior without contradicting annotations.

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 with two sentences plus a critical note. It is front-loaded with the main action and output, followed by an important caution. No unnecessary words.

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?

The description adequately covers the tool's purpose, output, and limitations despite no output schema. It mentions the output content (header, payload, summary) and expiry check. Missing details about error handling are minor for a simple decode 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?

Schema coverage is 100% with a single 'token' parameter described. The description does not add extra detail about the parameter beyond the schema, so a baseline of 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 title and description clearly state the verb 'decode' and resource 'JWT'. It specifies what is returned (header, payload, summary of claims) and distinguishes from siblings by its unique function. No other sibling tool decodes JWTs.

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 notes that the tool decodes but does NOT verify the signature, guiding the agent to use it for inspection only and not for trust verification. It implies appropriate usage contexts (offline, keyless) without alternatives needed due to no similar tools.

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