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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description only needs to add behavior. It does: results are indicative and based on the current barème, must be confirmed on france-renov.gouv.fr, and the reste à charge is returned only when a budget is supplied. It omits eligibility prerequisites (e.g. owner-occupier, dwelling age) and any input-validation behavior.

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?

Three sentences, front-loaded with the covered schemes and followed by the disclaimer; the bilingual duplication is mildly redundant but useful for retrieval. Nothing extraneous is present.

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?

An output schema exists, so return values need not be described. The description is nearly complete for a read-only estimation tool: it names the covered and non-covered aids and the confirmation source. It stops short of stating eligibility conditions or handling of missing/optional inputs.

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 carries the per-parameter burden and the baseline is 3. The description adds real meaning by explaining the interaction between budget_travaux_eur and the computed reste à charge, and by tying revenu_fiscal_reference to the income category (catégorie de revenus) used by MaPrimeRénov'.

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 states a specific verb (estimate) and a precisely scoped resource: French national subsidies for an air/water heat pump, enumerating the schemes covered (MaPrimeRénov', CEE, TVA réduite, éco-PTZ). It is trivially distinguishable from the sibling estimer_puissance_pac, which sizes equipment rather than computing subsidies.

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 implied (call this when you need aid amounts for a heat pump project) but there is no explicit when-to-use/when-not guidance and no reference to the sibling tool. The stated limits (amounts indicative, local aid not quantified) are scope disclaimers rather than routing guidance.

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