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

Annotations already declare readOnlyHint=true, and description adds that data comes from 'live medians (sale vs long-term rent, plus Airbnb when available).' It reinforces that it's not a property valuation. No contradiction; adds useful behavioral context beyond 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?

Two sentences, front-loaded with the core purpose, then scope clarification. No unnecessary words; every sentence adds value.

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 simple computation tool with 4 parameters and no output schema, the description is complete: explains data sources, scope, and limitations. Hints at return type ('gross rental yield'). Adequate for the complexity.

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 75%, so baseline is 3. The description does not add extra meaning beyond the schema; it mentions data sources but not parameter specifics like property_type enum or neighborhood fallback. No improvement over schema.

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?

Description states 'Gross rental yield for a zone, computed from live medians' with a specific verb (computes) and resource (rental yield). It distinguishes from valuation ('never a valuation of a specific property') and from sibling tools like mortgage_calculator or closing_costs.

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?

Explicitly says 'Zone-level market reference ONLY' and 'Use for "¿conviene invertir?" / rentabilidad / yield questions,' providing clear context. Does not list alternative tools for when not to use, but the sibling list includes other real estate tools, so context is strong.

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