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

The description adds real context beyond the annotations: a per-response cost of 0.02 EUR and a rule that availability must never be invented, which tells the agent the answer is authoritative and billable. It does not explain why readOnlyHint is false for a "read", nor what a "useful answer" versus a failure looks like.

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 short sentences, front-loaded with the action and immediately followed by the cost/no-fabrication constraint. Nothing is padded, though the terseness is part of why key information is missing.

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 three-required-parameter, zero-coverage, no-output-schema tool that also charges money, the definition is thin: no explanation of request_id's role, the budget ceiling, what fields a "fiche" returns, or what a failed/invalid lookup costs.

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 0%, so the description must carry parameter meaning and it does not: station_id, request_id (likely an idempotency key given the 8-128 char constraint) and max_cost_cents are never mentioned. The cost sentence hints at a budget cap but gives no relation to max_cost_cents.

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 gives a verb and a vague resource ("Lire une fiche") but never says the fiche is a station record, even though the tool name is station_context and siblings are search_stations/discover_plugtrip. An agent can infer it fetches station detail, but the description itself leaves the mapping implicit.

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?

There is no statement of when to call this instead of search_stations, nor any prerequisite (e.g. call after a search, or that a paid lookup requires a budget). Usage must be inferred from the tool name alone.

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