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

Annotations already declare readOnly/idempotent/closed-world, and the description goes further by explaining the return shape (valid true/false with a reason) and, importantly, the limits of what 'valid' means — not legal proof, notary, evidence, or certificate. That semantic caveat is exactly the kind of context annotations cannot convey.

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?

Three tight sentences with the core action front-loaded, followed by usage mapping and then the result/limits. No filler; each sentence carries distinct information.

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 correctly explains the return value and its interpretation, plus the non-guarantees. The only shortfall is the absence of per-parameter guidance, though that is primarily a schema-side gap.

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 only 14% — just api_key is documented — and the description does not compensate, saying only 'pass the receipt fields as arguments.' The meaning, format, and source of sha256, stamped_at, key_id, signature, statement, and public_key_url are left entirely to inference.

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 (verifies a stamp receipt), and ties it to the sibling workflow by saying the receipt comes from stamp_hash. An agent can immediately distinguish this read/verify tool from the stamping tool without opening either schema.

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?

Gives clear context: take the receipt produced by stamp_hash and pass its fields as arguments, mirroring POST /v1/verify. It does not explicitly state when NOT to use it or name alternatives, but the workflow position is unambiguous.

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