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

With no annotations, the description carries the full behavioral burden, and it delivers a genuinely useful trait: it distinguishes a real file from an SPA returning its HTML shell for unknown paths. That is exactly the kind of non-obvious behavior an agent needs. It stops short of describing the response shape or whether checks are batched per-path, so it isn't exhaustive.

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?

Three sentences, front-loaded with the core action, then the differentiating behavioral insight, then the usage cue. No filler, and the most decision-relevant material comes first.

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 one-parameter, no-annotation, read-style check with no output schema, the description covers purpose, the key false-positive pitfall, and a use case. It would be fully complete if it hinted at what the result reports (which files present vs absent), but nothing needed to invoke it 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?

There is a single parameter with 100% schema description coverage, so the schema already documents 'url' fully. The description adds no syntax, format, or scope detail (e.g. whether paths or a bare origin are accepted) beyond the schema, 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?

The description names a specific verb ('Check which ... files a website actually serves') and enumerates the resource set (llms.txt, robots.txt, sitemap.xml, MCP manifests). It cleanly separates itself from a generic scan by focusing on served discovery files, but it never names or contrasts against the sibling tools (citefiles_scan, citefiles_crawler_access), so sibling differentiation is left implicit.

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?

It gives a clear triggering context: 'Use this to verify a file you just published is being served correctly.' That tells the agent when to reach for this tool, but there is no guidance on when not to use it or which sibling to prefer for the adjacent jobs (scanning, crawler access), so it falls short of the explicit alternatives level.

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