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

Annotations already declare the safe-read profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still adds real context: corpus size (~109,812 facilities, ~32,883 active), the covered service classes, and the explicit exclusion of ownership data. It does not mention pagination or result ordering, which keeps it from a 5.

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 sentences with no filler: scope, corpus magnitude, returned fields, and boundary of coverage. The corpus statistics earn their place by setting result-set expectations. Slightly dense but well front-loaded.

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 and a trivial 2-parameter input, the description carries the return-value burden and does it: it enumerates the returned fields (service, channel, frequency, community, status, license expiration) and bounds the corpus. Nothing needed to call it correctly 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 description coverage is 100% and both parameters are documented in-schema (q as call sign/city with a >=2 char minimum; limit default 25 max 100). The description only restates that q accepts a call sign or community, adding no format or matching-behavior detail beyond the schema, so the baseline 3 applies.

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?

Specific verb+resource ("Search the FCC broadcast station directory") plus the exact lookup keys (call sign or community of license). The closing scope note ("Station facts only — no ownership") carves it away from the sibling fcc_grantee_search, which the agent can act on without opening a schema.

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?

The "no ownership" exclusion implies when to reach for an ownership-oriented sibling instead, but no alternative is named and no when-not conditions or prerequisites are stated. Usage is inferable from the scope note rather than explicit.

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