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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds non-obvious behavior: the response includes an upsell link and reflects only declared policy rather than actual enforcement. That distinction is genuinely useful context a schema would not convey.

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 tight clauses: what it returns, when to use it, and when not to. The scope/exclusion constraint is front-loaded after the purpose, with zero filler.

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 carries the return-value burden and does describe the verdict contents (allowed/blocked bots, upgrade link). It stops short of describing the verdict format or whether a verdict is always returned for non-existent robots.txt, but covers what an agent needs to call it correctly.

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% for the single url parameter, so the schema does the heavy lifting. The description adds only that the target must be a 'public website' or domain, which is consistent with but not richer than the schema's 'Public website URL or domain.'

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 (returns a site's robots.txt verdict for AI crawlers) and enumerates what the result contains (allowed and blocked bots, upgrade link). Clearly distinguishable from siblings read_url and find_tidytools_tool, which do unrelated things.

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?

Explicitly scopes usage to inspecting one public website's declared crawler policy, then states two concrete exclusions: not for proving CDN/firewall enforcement, and not for ongoing monitoring. No alternative sibling is named, but the when/when-not boundaries are unambiguous.

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