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

Annotations already cover read-only, idempotent, closed-world safety, but the description adds substantial context: the three fit verdicts and what each means, the caveat that unknown is not evidence of non-fit, and the presentation rule that adapter fits must never be reported as direct. It also mandates citation via the returned citation line and html_url.

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 core question, then the return shapes, then a clear output-fidelity rule. Dense but every sentence carries information; the reporting rule is slightly verbose but justified by the stakes.

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?

There is no output schema, so the description must describe return values — and it enumerates direct, adapter, unknown and needs_clarification with their payloads. It also supplies the citation obligation, so an agent has everything needed to answer and report 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% and documents slug-or-name inputs, so baseline would be 3. The description earns more by mapping the clarification retry to the parameters (returning candidates that the agent then passes back as a slug).

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: answering whether a specific red dot optic fits a specific pistol, from source-cited data. It is clearly distinguishable from sibling list/getter tools like get_footprint and list_pistols_for_optic.

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 operational rule for the ambiguous-name case (returns needs_clarification with candidates; call again with a candidate slug), which tells the agent how to proceed. It lacks an explicit statement of when to prefer this over get_footprint or the list tools, so it falls short of a 5.

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