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

Annotations already cover safety (readOnlyHint, openWorldHint), and the description adds meaningful context beyond that: the call is free, the result is a signed statement, and it points to the key at /.well-known/annalist-key.json for verification. It does not mention rate limits or caching, but the signing/verification detail is substantive.

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 decisive fact ('Free.'), then the trigger, then the payload and verification path. Every sentence earns its place with 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?

No output schema exists, so the description carries the burden and does so: it names the return contents (grade, key facts, reasons) and how to verify authenticity. For a one-parameter read tool, nothing essential is missing.

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?

Single required parameter with 100% schema description coverage ('host name or any URL of the service'), so the schema already carries the semantics. The description adds nothing about accepted formats or edge cases (e.g., whether path/query are stripped), which is the expected baseline when schema coverage is complete.

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 (get the signed Annalist check for an x402 service before paying), and enumerates the payload it returns: grade, uptime, price/wallet match, organic paying customers, test purchases, reasons. An agent can distinguish this from generic siblings like checks_service or checks_seller based on the title's explicit 'x402 service' scope.

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 a clear trigger condition: 'Before paying an x402 service'. That is a real when-to-use instruction, but no when-not-to-use or named alternative sibling is provided.

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