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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), but the description adds real behavioral context: longest-token-first matching, and that it returns the crawler record with cite line, the operator's verification method, or an undocumented-token entry. With no output schema, this return-value disclosure is genuinely useful.

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 purpose and kept to a few tight sentences; the API-equivalence note ('Same as GET ...') earns its place for routing. Slightly restates the title but not wastefully.

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 tool with no output schema, the description covers matching behavior, return shape, and the important caveat that a UA string is a claim, not proof. Only the caller's next step after identification is left implicit.

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 the single parameter 'ua' is already documented as the full User-Agent header value with a maxLength. The description adds no format or syntax guidance beyond the schema, so baseline 3 applies.

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 (identify) and resource (user-agent string matched against a crawler directory), and the title/description together make the operation unmistakable. No sibling tool does anything similar, so an agent can select it without confusion.

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 implies usage ('a user-agent string is a claim, not proof') and hints that the operator's verification method is the follow-up, but it never states when to prefer this over alternatives or what a caller should do with the result. Usage is inferable rather than explicit.

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