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

With no annotations, the description carries the burden. It does disclose a live-fetch behavior and a direct-text mode, which implies read-only linting rather than modification. However, it does not describe output format, error behavior, or what happens if both parameters are supplied, leaving some behavioral traits implicit.

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?

A single sentence that front-loads the main purpose and then gives the two invocation modes. There is no filler and every clause adds useful information.

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 simple tool with two optional parameters and no required inputs, the description covers purpose and invocation modes adequately. Minor gaps include not describing the return value and not explicitly stating precedence when both params are provided, but the schema already hints at 'instead of fetching url', so the overall context is sufficient.

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 schema already documents both parameters well. The description mostly restates the schema's 'fetch' and 'directly' semantics without adding meaningful new parameter-level detail, so the 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?

The description states a specific verb ('Lint'), a specific resource ('robots.txt'), and a specialized scope ('AI-crawler-specific mistakes'). This clearly distinguishes it from sibling tools like validate_llms_txt and check_site.

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 clear invocation guidance: pass url to fetch live, or pass robots_txt to lint pasted text directly. It does not explicitly name when-not-to-use alternatives or exclusions, so it stops short of a 5, but the intended usage context is unambiguous.

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