robots.txt check

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

Annotations already declare read-only, open-world, idempotent, and non-destructive behavior. The description adds meaningful behavioral context beyond those hints: it performs a network fetch from the first URL's origin, applies Google's longest-match rules, and defaults to Googlebot. This helps an agent understand external dependencies and evaluation logic.

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?

One well-structured sentence covers the main action, the output components, the input behavior, and the matching algorithm. There is no filler, and the most important action ('Fetch a site's robots.txt') is front-loaded.

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 no output schema, the description still conveys what the agent will receive: groups, sitemap lines, and crawlability results. It could be more explicit about the shape of crawlability results or error cases like missing robots.txt, but the current level is sufficient for a read-only diagnostic tool.

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 only 50% (userAgent lacks a description), but the description compensates by explaining that userAgent defaults to Googlebot and that crawlability is tested using Google's rules. It also reinforces the schema note that robots.txt is fetched from the first URL's origin. This is enough for correct invocation.

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 names a specific resource (robots.txt) and concrete actions (fetch, show groups/sitemap lines, test crawlability). It also clarifies the rules engine (Google's longest-match) and default user agent, making the tool's function distinct from siblings like sitemap_check or ai_crawler_access.

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 when you need a site's robots.txt rules, sitemap references, or crawlability checks for a specific user agent. It does not explicitly mention when not to use it or name an alternative, but the use case is unambiguous enough for an agent to route correctly.

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