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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful behavior (it merges into existing robots.txt and returns the full new file plus a diff), but it leaves the critical ambiguity unresolved: whether rules are actually applied to the live site or merely returned for the caller to apply, which is the one thing an agent most needs to know here.

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 action and target, then the policy vocabulary, then the return value. No redundant restatement of the title or annotations; every clause carries 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?

With no output schema, the description correctly explains the return payload (full new robots.txt and what changes), and both parameters are documented. The gap is merge semantics: it never says whether existing rules are preserved or overwritten, nor whether the result is applied live, which matters for a tool that edits a site's crawler policy.

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 the baseline is 3, but the description genuinely enriches the enum beyond the schema's terse 'Which AI crawlers to allow' by defining search_only as allowing AI search and user-requested fetches while blocking model training, and noting block_training is an alias. The url parameter's 'any page of the site' semantics come only from the schema.

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 gives a specific verb pair and resource: write robots.txt rules for AI crawlers and merge them into the site's current robots.txt. The purpose is unmistakable and functionally distinct from sibling tools like test_robots or generate_llms_txt, though no sibling is named explicitly to make the boundary airtight.

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 through the enumerated policy modes (allow_all, search_only, block_training, block_all), each paired with a behavioral gloss, which tells the agent what each input means. However, there is no explicit guidance on when to choose this tool over test_robots or generate_llms_txt, and no stated prerequisites.

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