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

With no annotations, the description carries the full behavioral disclosure burden, and it does so thoroughly: it reveals pay-to-access behavior, exact pricing per request mode, the USDC-on-Base payment address, the requirement for a valid X-PAYMENT, HTTP 402 when unpaid, and JSON return after payment. It also discloses chunking semantics and the difference between one official text and chunked responses.

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 dense but front-loaded with the endpoint and price, then systematically covers the different request modes and payment behavior. Most clauses carry necessary information, though 'Not a new SKU' is cryptic and the long sentence structure could be more readable. It is appropriately sized for a paid, multi-mode endpoint.

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?

Given there is no output schema and no annotations, the description covers the essential operational details: payment, auth header, chunking, id lookup, watermark semantics, and error behavior. It does not describe the JSON response shape or pagination beyond what the schema implies, but it provides enough for an agent to invoke the tool correctly.

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%, so the baseline is 3. The description adds meaningful value beyond the schema by associating each request mode with a cost ($0.05 vs $0.02 for id) and clarifying that id returns 'one official text' while plain GET returns a chunk. This enrichment helps an agent choose parameters with cost awareness.

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 description clearly states the tool's function: GET FDA warning-letter bodies via a paid endpoint, either as the newest chunk or a specific official text by id. It identifies the resource with 'FDA warning-letter bodies' and the HTTP verb, making the tool's purpose unambiguous. However, it does not explicitly distinguish this endpoint from its many siblings beyond the FDA domain, so it falls just short of a 5.

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 gives clear operational guidance: plain GET returns the newest chunk, ?id returns one official text, ?before fetches an older chunk, and ?since fetches newer-than-watermark items. It also explains the payment requirement and HTTP 402 behavior. It does not compare against sibling tools or state when not to use this tool, so it lacks explicit alternatives guidance.

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