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

The description discloses extensive behavioral details beyond annotations: pagination (50 per page, pages 1-10), ordering (newest first), total count, use of a residential proxy, and precise pricing ($0.002 per successful call via x402, failed calls not charged). This is rich transparency for a read-only tool.

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 single, front-loaded sentence that packs all critical information (purpose, fields, pagination, cost, proxy) without any filler. It is appropriately dense given the tool's complexity.

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?

Given a read-only listing tool with an output schema, the description covers all essential aspects: input format, pagination, ordering, pricing, and proxy usage. Nothing an agent needs to call it correctly 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 description coverage is 100%, so the schema already documents both parameters. The description adds that the area is a Hemnet location id from a search URL and gives an example (17744 = Stockholms lan), which is helpful but largely redundant with the schema's own descriptions.

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 specific verb and resource: 'Hemnet (Sweden) homes for sale in an area', and lists the fields returned, making the purpose clear. It distinguishes itself from other real estate tools by naming the source (Hemnet) and country, but does not explicitly name sibling alternatives.

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?

Usage is implied: it's for retrieving Hemnet listings by area, with the locationId format explained. However, there is no explicit guidance on when to use this tool versus other real estate listing tools, nor any exclusions (e.g., not for rentals or other countries).

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