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

Annotations already declare readOnly/idempotent/openWorld, so the bar is low; the description still adds real context beyond them: data source (api.fr.openfisca.org), a 24-hour cache, dated historical values, legal references, and a caveat to check the official text. It stops short of describing error behavior for invalid paths or pagination/truncation of the partial-path listing.

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 core purpose, followed by examples, the partial-path rule, and the source/cache caveat; every sentence carries information. The FR/EN duplication doubles the length, which is the main efficiency cost.

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 explains what comes back (value at date, dated history, legal references). Combined with annotations covering the safety profile and full schema coverage, an agent has enough to call it correctly; only edge-case behavior (invalid path, result limits) is missing.

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 coverage is 100%, so the baseline is 3, but the description adds meaning beyond the schema: the date defaults to today and a partial name path returns a list rather than a single value, which directly explains the name parameter's behavior. It does not elaborate on the historique semantics beyond what the schema already says.

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 resource (French socio-fiscal legislation parameter from OpenFisca France) and what it returns (value, dated history, legal references). The two concrete path examples (impot_revenu.bareme_ir_depuis_1945.bareme, taxation_capital.pfu.taux) make the domain unambiguous versus siblings like bofip_get or legifrance_article.

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 clear operating context: default date is today, a partial path returns the list of matching parameters, and results should be verified against the official text. It does not explicitly name when to prefer a sibling (e.g. legifrance_article for the authoritative text), so exclusions are absent.

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