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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description still adds substantial context beyond them: cost ('Free; no API key needed'), the tier concept with its gating condition ('restricted' endpoints need the account's restricted-endpoint terms accepted), and the exact shape of the compact result set including credits per call.

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 its scope in the first clause, then evidence, then the return contract. Four sentences, each carrying distinct load (purpose, urgency/scale, query syntax, return fields and cost); nothing is repeated from the schema or annotations.

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?

No output schema exists, and the description compensates by enumerating the returned fields (endpoint ID, name, HTTP method, credits per call, tier, required parameters), which is exactly what an agent needs to decide whether to call this or a sibling. Nothing material is missing for a 3-parameter read-only search.

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 schema carries the baseline; the description still adds value with four worked query examples ('amazon product reviews', 'zillow property', etc.) that teach the expected query phrasing. It does not mention the optional 'vertical' filter or the limit range, leaving those purely to the schema, which keeps it below a 5.

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 ('Find Perceptlayer endpoints') and immediately scopes it to a website or kind of data. It also distinguishes itself from siblings by naming get_endpoint and call_endpoint as downstream steps, so an agent knows this tool only locates, never fetches.

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 instructs 'search before calling' with the reason (1659 endpoints across 248 sources), which is a clear when-to-use rule rather than an implied one. It also names the alternative tools and the exact handoff value (endpoint ID) that selects them, completing the workflow routing.

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