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

Annotations already declare readOnly/idempotent/openWorld, so the bar is lower; the description still adds real value by naming the data source, the crawl-purpose categories, and the found:false edge case for unknown user agents. No mention of rate limits or latency, but nothing contradicts the annotations.

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 resource and the crawler list, then the dimensions and the user_agent caveat. Dense but every clause carries information; only the inline parenthetical example list is slightly bulky.

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?

Output schema exists, so return-shape explanation is unnecessary, and the description covers scope, dimensions, location, and the user_agent lookup path. Complete enough to call correctly, with only minor gaps around limits/pagination expectations.

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. The description goes beyond the schema by explaining what crawl_purpose means (training, search, user action) and what happens with an unrecognized user_agent, which the schema alone does not convey.

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 — AI crawler traffic shares from Cloudflare Radar — and enumerates the concrete crawlers and the three grouping dimensions. An agent can distinguish this from radar_top_domains or radar_domain_rank purely from the text.

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 says to pass user_agent for a single crawler's share and that unknown agents return found:false, plus lists the dimension options and global-vs-country scope. It stops short of naming when to prefer the sibling tools (e.g., ai_visibility_check, radar_top_domains) over this one.

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