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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior. The description adds meaningful context beyond those annotations: price provenance is included and no Pillr score is returned, which sets expectations about what the agent will and will not get back.

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-loads the comparison scope and then moves cleanly to usage and alternatives. The first sentence is long because it enumerates all indicators, but each item is relevant to tool selection; only that density keeps it from being a 5.

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 read-only tool with rich annotations, one fully documented parameter, and no output schema, the description is nearly complete: it lists returned indicators, provenance, and the absence of a proprietary score. It does not describe response structure or missing-data behavior, which is a minor remaining gap.

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?

With 100% schema description coverage, the schema already documents the accepted commune formats, INSEE codes, arrondissement syntax, postal-code fallback, and the 2–5 item bounds. The description only reaffirms the 2–5 range and cross-references the commune parameter of other tools, adding modest value over the schema.

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 and resource — comparing 2 to 5 French communes — and enumerates the exact indicators compared. It explicitly distinguishes itself from marche_commune and classement_departement, so an agent can route correctly without opening schemas.

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 an explicit trigger: use whenever a question puts several communes in balance, with a concrete example. It also names the alternatives for single-commune detail and unnamed-commune discovery, covering when not to use it.

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