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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false; the description reinforces this by clarifying it performs no network fetch and returns stored card data. That adds useful context beyond the annotations, though it says nothing about auth needs, error behavior for unknown ids, or pagination.

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 compact sentences: the retrieval contract is front-loaded, followed by the negative constraint. No filler, no repetition of the title.

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 single-parameter, read-only lookup with no output schema, the description covers both the lookup key and the shape of the returned card (source URL, read date), and rules out misuse modes. Nothing needed to call it correctly 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?

Schema description coverage is 100% and the id parameter is already documented with concrete examples (gptbot, google-extended), so the description only restates 'by id'. The negative enumeration of forbidden parameters is the one addition, but no id syntax, format constraints, or prefix conventions are supplied beyond the schema.

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?

Specifies the verb (return), the resource (one card), and the retrieval key (by id), plus what the payload contains (vendor source URL and read date). An agent can distinguish this single-card reader from list_crawlers 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?

Explicitly states what this tool does NOT do ('does not fetch any website') and enumerates parameters it must not receive (url, host, target, website, robots_url, fetch) — a strong exclusion list. However, it never names the sibling tool an agent should call instead for fetching or listing, so routing guidance is implied rather than complete.

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