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

With no annotations, the description carries the full burden and does meaningful work: it discloses per-call cost ($0.005 via x402, USDC on Base) and that responses carry a provenance chain and Ed25519 attestation, which is real trust/verification context. It omits auth failure modes, whether payment is mandatory for a result, and any rate limits.

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?

Two tight sentences, front-loaded with what the tool returns and followed by cost/trust metadata; there is no filler. It could be marginally better organized by separating the price/attestation clause from the data clause.

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 with no output schema, the description covers the returned fields, the cost model and the attestation guarantee, which is close to what an agent needs. The main gap is the required `id` parameter's format and a lack of routing guidance against sibling summary tools.

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 50% and the undocumented parameter is the required one: the description never explains what `id` is, its format, or how to obtain a valid site identifier beyond the vague phrase 'one monitoring site'. The free-quote/payment-header details live entirely in the schema, so the description adds almost no parameter meaning.

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+resource with scope: a current EPA AirNow observation for 'one monitoring site', returning AQI value, category and reporting parameter. The 'one monitoring site' scope implicitly separates it from the sibling aqi_category_summary, so an agent can distinguish them without opening either 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?

Usage is only implied by the singular scope ('one monitoring site'), which suggests single-site point queries rather than aggregate summaries. It names no alternative tool and gives no explicit when-not condition, so routing against aqi_category_summary is left to inference.

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