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

Annotations already establish readOnly, idempotent, and non-destructive behaviour. The description adds meaningful behavioural context: comparables are drawn from a band around the reference price unless maxPrice overrides it, and the tool answers a pricing-adequacy question rather than a textual-match question. No annotation contradiction exists.

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 three sentences with no filler: it states the core function first, then usage examples, then the crucial distinction from text search. Every sentence adds information needed to invoke the tool correctly.

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 tool with three parameters, full schema coverage, and an output schema, the description covers the key decisions an agent must make: when to call it, what makes properties comparable, and how maxPrice changes behaviour. The output schema handles return-value documentation, so nothing essential is missing.

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 coverage is 100% and each parameter is well described in the schema. The description adds extra semantics for maxPrice ('overrides the default band', 'similar but cheaper') and clarifies slug as the reference listing. This is above baseline but not dramatically richer than 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 uses a specific verb and resource: 'Given one listing, find comparable ones' and defines comparability dimensions (operation, area, typology, floor area, price). It also explicitly distinguishes itself from text-similarity search, so an agent can tell it apart from search_properties_by_description.

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 states exactly when to use the tool with user-intent examples like 'find me something similar' and 'the same but cheaper'. It also explains the maxPrice behaviour for the cheaper case and explicitly contrasts with keyword search, which is a clear when-to-use versus alternative.

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