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

Annotations already declare readOnlyHint and openWorldHint, and the description is consistent with them. It adds real behavioral context beyond the annotations: RFC 9309 matching semantics, the 17-crawler coverage set, per-crawler verdicts with the deciding rule, and a disclosed daily rate limit for unauthenticated use. Not mentioned: behavior when robots.txt is absent or unreachable.

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 front-loaded sentence carries the core action, resource, scope, and output shape, followed by two short clauses on matching standard and access cost. No filler and no repetition of schema fields verbatim.

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 does the necessary work by specifying what is returned (allow/deny per crawler plus the governing rule). The one gap is the error/edge behavior for sites with no robots.txt or that are unreachable, which matters for a single-fetch open-world 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 100%, so the baseline is 3, but the description adds a level of meaning the schema lacks: it clarifies that 'url' yields a home-page check by default and that 'path' extends the check to a specific page, which is exactly the interaction between the two parameters an agent needs to reason about.

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 ('Read a site's robots.txt and report') plus the precise output dimension: per-crawler allow/deny decisions for home page and an optional path, with the deciding rule. This clearly distinguishes it from scan_site and the other scan/issue siblings, which operate on whole-site scans rather than a single robots.txt fetch.

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 narrow scope (robots.txt, specified crawlers, single path), and the 'works without an API key (limited per day)' note hints at a cheap pre-flight use. However, it never explicitly says when to prefer this over scan_site or get_scan, nor states exclusions or prerequisites such as the site being publicly reachable.

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