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

With no annotations, the description carries the full burden, and it does disclose concrete behavioral traits: $0.01 per call settled via x402 (USDC on Base) and a response containing a provenance chain and Ed25519 attestation. It stops short of covering failure modes, rate limits, or auth prerequisites beyond payment.

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 sentences with zero waste: purpose first, then the payment and provenance details. Every clause earns its place and nothing is buried.

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 no-annotation, no-output-schema tool, the definition adequately covers what it does, its cost model, and its verifiability guarantees. It could still clarify what 'AQI categories' and the 'reporting area' mean, which matters for interpreting results.

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% for the single payment parameter, which already documents the base64 x402 header and the free-quote fallback. The description adds no parameter meaning beyond that, 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?

States a specific verb+resource: EPA AirNow observations aggregated into AQI categories with site counts per category. The aggregation framing implicitly distinguishes it from the sibling aqi_site_lookup, but it never names that alternative, so it falls short of full sibling differentiation.

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?

No explicit when-to-use or when-not-to-use guidance and no named alternatives. Usage is only implied by the 'aggregated into categories' framing versus the site-level lookup sibling, leaving the agent to infer the routing condition.

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