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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds substantial context: the 24-month DVF window, median sale price/m², ANIL charges-included rent/m², gross yield, confidence interval, data-quality flags, cost of 10 credits, and excluded cost categories. This is rich behavioral disclosure beyond the 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?

Front-loads the purpose, then cleanly separates REQUIRED, OPTIONAL, Returns, Important caveats, and Cost. Despite moderate length, every section is useful and easy to scan.

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?

There is no output schema, so the description must explain return values, and it does: latest 24-month DVF window, median sale price/m², ANIL rent/m², estimated gross yield, confidence interval, and data-quality flags. It also clarifies scope limitations and cost, making the definition complete for correct invocation.

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 groups parameters as required/optional and repeats examples/defaults already present in the schema, adding no new syntax or format detail beyond what the schema 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?

States the specific verb ('Estimate gross rental yield') and resource ('one French commune') and names the data sources (ANIL asking-rent indicators, clean DVF sale prices). It explicitly distinguishes itself from a property valuation, which is important given sibling tools like estimate_property_value.

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?

Provides clear context that this is a commune-level estimate and explicitly excludes property-level valuation, helping agents avoid misuse. However, it does not name alternative sibling tools or give detailed when-to-use conditions for comparing yields versus other analytics.

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