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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds valuable behavioral context: the result is ESTIMÉ, non garanti, and the hypotheses (rendement, revalorisation, fiscalité) are provided by the caller. It also names the underlying method (actualisation de flux, TRI). This goes beyond the annotations without contradicting them.

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?

The description is compact and front-loaded with the core purpose, then lists outputs, then states the estimated nature, then routes to alternatives. The parenthetical source note is slightly extra but useful. No wasted words.

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 projection tool with 100% schema coverage and no output schema, the description covers the purpose, the key outputs, the estimated nature, and the alternatives. It does not describe the exact return shape, but since there is no output schema and the tool is a projection, the description is reasonably complete. A small gap is the lack of detail on how versement_mensuel and reinvest_dividendes interact, but the schema covers their existence.

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 8 parameters. The description adds context about the overall hypothesis set (rendement, revalorisation, fiscalité) but does not add per-parameter meaning beyond the schema. Baseline 3 is appropriate.

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 ('Projette'), a specific resource ('un investissement en SCPI au comptant'), and the key outputs (valeur brute/nette de revente, revenus distribués, TRI). It also explicitly distinguishes itself from sibling tools simulateurs_scpi_credit and simulateurs_demembrement_scpi, making it easy for an agent to select the right tool.

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?

The description explicitly says when to use this tool (SCPI au comptant) and when not to: 'Achat à crédit → simulateurs_scpi_credit ; nue-propriété ou usufruit → simulateurs_demembrement_scpi.' This is clear routing guidance with named alternatives.

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