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

With no annotations, the description carries the burden well: it discloses paid access ($0.05 USDC per call via x402, _meta["x402/payment"]), the free 3-row sample mode, and the non-obvious default filter that silently hides big-city markets. It does not cover rate limits, error behaviour, or max page size.

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?

A single dense paragraph that front-loads the concept and the locality definitions, then packs sources, routes and pricing into compact clauses. Nearly every clause carries decision-relevant information; nothing is padded.

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?

No output schema exists, and the description implies the return is rows of market places with a locality tag and a 3-row cap in sample mode, plus attribution/licence context. Response shape, pagination semantics and the meaning of limit/offset maxima remain unstated.

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 100% and the params object is a free-form additionalProperties map, so the schema alone cannot tell an agent which keys each route accepts. The description compensates by spelling out per-route params with required markers (lat*, lon*, q*, country*) and defining the locality values.

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-less but precise resource: 'Every recorded market place in the world tagged by how far it sits from cities', with an explicit locality taxonomy. An agent can distinguish it from the sibling `markets` by the rural/remote framing, though the sibling is never named outright.

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?

Gives the crucial default behaviour ('only regional and remote markets'), the full list of available routes with their required params, and a free-preview escape hatch via sample=true. It lacks an explicit exclusion statement such as 'for urban/general markets use the `markets` tool instead', which keeps it below 5.

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