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

Annotations already mark this as read-only and idempotent, and the description adds valuable context: the result is ESTIMÉ, non garanti, and depends on caller-provided assumptions for yield, revaluation, and taxation. It also cites the financial method used, which helps an agent set expectations beyond the annotation hints.

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 well structured: it front-loads the resource and outputs, then adds the estimation caveat and sources. It is slightly longer than strictly necessary because it repeats the title phrase 'SCPI au comptant — projection à terme', but each clause still contributes meaningful information.

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 compensates by naming the key outputs and the estimation nature, which is sufficient for a read-only projection tool. It could have explicitly noted the monthly payment parameter, since 'au comptant' might misleadingly suggest lump-sum only, but the schema covers that detail.

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 fully documents all 8 parameters. The description only summarizes hypothesis categories (rendement, revalorisation, fiscalité) without adding details beyond the schema, which matches the baseline of 3.

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 uses a specific verb ('Projette') and resource ('investissement en SCPI au comptant') and lists concrete outputs: valeur brute/nette de revente, revenus distribués, TRI. The phrase 'au comptant' also differentiates it from siblings like simulateurs_scpi_credit and simulateurs_demembrement_scpi.

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 'au comptant' framing gives clear context: this tool is for cash SCPI investment projections, not credit or démembrement variants. However, it does not explicitly name alternative tools or state when-not-to-use conditions, so it stops short of full exclusion guidance.

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