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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description still adds value by describing the produced output ('the file text, a per-crawler summary and notes') and asserting no side effects, though 'Read-only: it only returns text and changes nothing' largely restates the annotations.

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 action and packed with the parameter surface in one dense sentence, then the output and no-side-effect notes. The read-only sentence is partly redundant with annotations, but overall there is little waste.

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?

With a rich 9-parameter schema, full description coverage, an output schema, and comprehensive annotations, the description supplies enough for correct invocation. It is slightly short on tool-selection guidance against the validate/check siblings, but nothing needed to call the tool 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%, so every parameter is already documented in the schema with constraints (path syntax, token pattern, max counts). The description names the parameter groups at a high level but adds no syntax, format or default detail beyond what the schema provides, so the baseline of 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 and artifact ('Build a robots.txt') and enumerates the exact input surface (per-category choices, per-token overrides, default policy, paths, sitemaps, custom rules). This clearly distinguishes it from siblings like validate_robots and check_site, which assess rather than generate.

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?

Usage is implied by the generation framing, and the note 'Same engine as POST /api/generate' gives an equivalence hint. However, there is no explicit when-to-use vs when-not guidance, and no routing against validate_robots (validate an existing file) or check_site, which an agent choosing among four tools would want.

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