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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds key behavior: no income during démembrement, full ownership recovery at term, usufruct income net of IR and amortization, reliance on Qotien's cIR, and that the result is ESTIMATED. No contradiction with annotations.

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 a dense single paragraph: it front-loads the purpose, then behavior, routing, and sources. Each clause carries information, but the source list and multiple clauses make it slightly heavier than strictly necessary.

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 7-parameter simulator with no output schema, the description explains the model and inputs but does not describe the shape or units of the projected result, leaving an agent to infer what the tool returns. It also omits edge-case behavior and expected output metrics.

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 baseline is 3. The description adds model context (nue-propriété vs usufruit, market hypotheses provided by caller) but doesn't add parameter-level semantics beyond what the schema already provides.

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 precise action ('Projette un investissement en nue-propriété de SCPI et l'usufruit correspondant'), identifies the asset class and structure, and differentiates from siblings by explicitly routing full-ownership cash/credit cases to simulateurs_scpi and simulateurs_scpi_credit.

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?

It gives explicit routing: 'Pleine propriété au comptant → simulateurs_scpi ; à crédit → simulateurs_scpi_credit,' which tells the agent not to use this tool for those cases. It also clearly implies this tool is for démembrement specifically, meeting the when/when-not/alternatives criterion.

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