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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description does add value by disclosing the return format (full HTML in the response, no file/URL/PDF) and the default taux_km behavior, which matters given no output schema. It stops short of richer behavioral context, so a 3 is appropriate.

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?

Efficient and front-loaded: the WHEN clause leads, followed by output format, trajets shape, and the taux_km default. Slightly dense with parentheticals, but every sentence carries information.

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 correctly compensates by specifying the return format (HTML in-response, no file/URL/PDF). Combined with usage routing and the taux_km default, it is nearly complete; only minor details of the journal rendering are unspecified.

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 the schema already documents all six parameters. The description restates the trajets[] shape ({date, depart, arrivee, km, motif}) and mentions taux_km is optional with a server default, adding minor clarification over an already complete schema – baseline 3.

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 purpose (mileage log justified at the kilometric barème plus indemnities) with a clear verb/resource and explicitly names the sibling note_frais for a different case. An agent can distinguish it from siblings 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?

Front-loads 'QUAND' with the exact condition (déplacements justifiés au barème kilométrique) and routes the contrasting case (frais réels sur justificatif) to note_frais. Explicit when-to-use and when-to-use-an-alternative guidance.

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