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

Annotations already declare readOnlyHint, idempotentHint, closed-world and non-destructive, so the safety profile is covered. The description adds real behavioural context beyond that: the data source (comparateur du Médiateur national de l'énergie), weekly refresh cadence, and the significant asymmetry that C4 returns only a supplier count because C4 pricing is quote-only.

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-loaded with the verb and the core scope, and every clause carries information — segment limits, returned facets, the C4 exception, and the provenance/cadence. The first sentence is very dense (a colon-delimited enumeration spanning both segments before the C4 caveat), which costs a little readability but no filler.

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 zero parameters, a full read-only annotation set and an output schema present, the description covers everything the agent needs: what the tool is, which segment it serves, what happens for the other segment, and how fresh/sourced the data is. Nothing relevant is missing for correct invocation.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. The description does not need to explain argument semantics, and the segment behaviour it describes (C5 vs C4) is output-side, not argument-side.

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 definition names a specific verb ("Lit le catalogue vérifié") plus the exact resource domain (offres d'électricité professionnelles, segment C5 jusqu'à 36 kVA) and enumerates the returned facets: active offer count, suppliers, published all-in price spread, fixed/indexed split, last weekly reading date. This scope is unmistakably distinct from every sibling (analyze_bill, simulate, assess_ppa, etc.), so an agent can route to it without opening the 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?

Usage is only implied: the tool answers 'what does the professional offer market look like for C5' and explicitly scopes itself to that segment, including the C4 behaviour. There is no statement of when to prefer this over siblings such as simulate or analyze_renewal_terms, and no prerequisites or exclusions.

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