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

Annotations only cover safety (readOnly/idempotent/openWorld); the description goes well beyond them by disclosing default ranking (scheduled-service airfields first), truncation signaling via truncated/total_matching rather than silent dropping, and the found:false contract for zero matches. That is exactly the behavioral context an agent cannot get from structured fields.

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 scale and match target, then narrowing facets, then the sibling disambiguation, then the truncation and not-found contracts. Four dense sentences with no repetition and every clause carrying decision-relevant 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?

Five optional params, no output schema, and the description still covers ranking, pagination, truncation reporting, and the zero-result contract. Nothing an agent needs in order to invoke this correctly or interpret its result is missing.

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 baseline is 3, but the description adds real value: it enumerates the full range of type values (including 'closed', 'seaplane_base', 'balloonport') where the schema only gives three examples, and explains how limit/offset interact with truncation signaling.

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 (Search) and resource (OurAirports dataset, ~86,000 airfields) plus the exact fields matched (name, municipality, ident) and the two optional narrowing facets. It explicitly contrasts with ourairports_lookup, but leaves the near-identical sibling search_airports (and get_airport) undistinguished, so an agent still faces one ambiguity.

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?

Gives explicit when-to-use ('find airfields by partial name/city when you do not already have a code') and when-not ('ourairports_lookup requires an exact code'). It also prescribes recovery behavior on truncation ('narrow the query or page with limit/offset'), leaving nothing to inference.

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