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

Goes well beyond the readOnly/openWorld/idempotent annotations: it discloses the empty-result behavior (404, not charged), the payment model (x402 USDC on Base, $0.001 per successful call), and the no-payment response (a PaymentRequired object). This is exactly the kind of auth, cost, and failure-mode context an agent needs before invoking a paid tool.

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-loads the usage trigger, then moves through results shape, data source, error behavior, and pricing in three tightly packed sentences with no filler. Every clause carries information an agent can act on.

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, the description compensates by naming the returned fields, and it also covers the error case and the payment handshake. Nothing material is missing for an agent deciding whether and how to call this tool.

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 (q, limit) are documented there, including default and range. The description restates the default 5 / max 10 constraint rather than adding new semantics, so the baseline of 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 and resource ('geocode search' returning up to limit matches, each with lat/lon, display name, type, country), which clearly separates it from the single-result sibling geocode via the 'up to limit matches' framing. It references the /v1/geocode endpoint rather than naming the sibling tool, so differentiation is implied rather than explicit.

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?

'Use for autocomplete-style place pickers or when the query is ambiguous' gives a clear positive selection criterion, which implicitly steers unambiguous lookups to the single-result geocode tool. No explicit exclusion or named alternative is stated, so it stops short of the 5 level.

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