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

Annotations already cover the safety profile (readOnlyHint, openWorldHint, destructiveHint=false), but the description adds non-obvious behavior the annotations cannot: a hard coverage cap of five relationships per buyer, the 404 outcome and its meaning, and BETA status / ES-FR-only data. It stops short of describing response shape or any rate/credential constraints, but the dataset-limitation disclosure is the valuable part here.

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, front-loaded with the dependency concept followed by the returned fields, then the coverage limit and fallback. Dense but every clause carries information; the long enumerated field list is justified because there is no output schema to carry it.

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 enumerating the returned metrics, and it also covers the two failure-relevant facts (top-five-only coverage and 404 behavior) plus jurisdiction limits. For a three-parameter, read-only lookup this is enough for an agent to call it correctly and to interpret an empty result.

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%, so buyer (DIR3/NIF, SIRET), supplier (NIF, SIREN) and the country enum with its ES default are already fully documented in the schema. The description only reinforces the geographic scope; it adds no per-parameter format or constraint detail beyond what the schema supplies, 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?

The description names a specific resource (buyer-supplier dependency for a public buyer and one of its five largest suppliers) and enumerates exactly what each record contains — awards, awarded value, supplier share, first/last award, single-bid awards, average bids, insolvency date. It also scopes it geographically (Spain or France, BETA), so an agent can distinguish it from procurement_buyer and procurement_awards without opening any 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?

It states the hard precondition — only the five largest relationships per buyer are held, and anything outside returns 404 — and names the concrete fallback, procurement_awards, for a supplier's full award list. That is an explicit when-not-to-use rule plus a named alternative, not an inference the agent has to make.

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