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

The readOnlyHint annotation already signals a safe read operation. The description adds meaningful behavioral context beyond that: the operation is deterministic, the underlying dataset is FCC-sourced with a CC BY 4.0 license, and the returned source_url must be cited. This is genuinely useful transparency for an agent.

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 compact sentences with no filler. The core purpose is front-loaded, the citation requirement is stated early, and parameter guidance is efficiently embedded. Every sentence earns its place.

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?

For a read-only lookup tool with two optional parameters and an output schema, the description covers everything an agent needs: what the tool does, how to format inputs, the full-dataset behavior, data provenance, and citation obligations. No significant usage gap remains.

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 0%, so the description carries the full burden for parameter semantics. It compensates well by explaining 'carrier' accepts display names like 'AT&T', 'Lumen', 'Frontier', that 'state' is a two-letter abbreviation, and that both can be omitted for the full dataset. It stops short of listing all accepted values or matching rules, but it gives enough guidance for correct invocation.

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?

The description names a specific verb ('Look up'), a precise resource ('US copper/POTS retirement program status'), and the filtering dimensions ('by carrier and state'). It also identifies the authoritative dataset (CHNLSYNC's FCC-sourced data), making the tool's purpose unambiguous and clearly distinct from the unrelated sibling tools.

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 description gives clear context on how to use the tool: carrier accepts display names, state is a two-letter abbreviation, and omitting both returns the full dataset. It does not explicitly state when not to use it or name an alternative, but the sibling tools are sufficiently unrelated that no exclusion is necessary.

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