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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint, so the description does not need to repeat that this is a non-mutating read. It adds extra context with 'Requires a Nautilinks API key' and the open-ended 'any other published attributes,' but it does not describe error behavior, invalid-id behavior, rate limits, or output shape variations.

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 front-loads the usage context in the first sentence, then gives an efficient purpose statement and a necessary API-key note. The list of fields is longer than strictly necessary, but it earns its place because there is no output schema.

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 tool with full annotations and no output schema, the description says what the tool does, when to invoke it, what the return will contain, and which prerequisite it needs. An agent has enough context to select and call this 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?

The schema provides 100% documentation for site_id: 'The catalog site id, as returned by search_sites.' The description merely says 'by id' and does not enrich the parameter semantics further, so the schema already carries the documentation burden.

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 uses a specific verb and resource: 'Fetch the full catalog record for a single site by id,' and enumerates the returned fields. It explicitly distinguishes this from the search_sites list stage by saying 'Use this after search_sites,' so it is not just a tautology of the tool name or title.

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 context: 'Use this after search_sites when the user needs to evaluate one backlink placement before buying.' It names the predecessor search_sites and the intended workflow stage, but does not explicitly state when not to use the tool or mention an alternative tool that should be selected instead.

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