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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so this is additive credit: the description discloses response language behavior ('Spanish for language es and in English otherwise') and a non-obvious rendering rule that links must be shown exactly as returned including query parameters. That link-preservation instruction is real behavioral guidance an agent could otherwise violate.

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-loaded with purpose and identifier forms, then the return contents, then language and link rules. Dense and mostly waste-free, though the long enumerated contents list overlaps with the output schema.

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 read-only single-record lookup with an output schema and full schema coverage, this covers what an agent needs: identifier forms, language behavior, what is returned, how to reach the agent, plus the link-rendering constraint. Nothing material 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%, so the baseline is 3; the description earns more by clarifying what the vague 'Language of the user' parameter actually does — it selects the output language of the description and resolves the non-obvious case of the ru/de/fr/nl/sv/no/pl enum values falling back to English. The reference examples partly restate the 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?

States a specific verb+resource ('Full details of one EVS listing') and clearly scopes it to a single record identified by reference or URL. The singular 'one listing' implicitly separates it from search_properties and list_locations, but no sibling is named explicitly.

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 only implied — the agent must infer this is the tool for when it already has a reference or URL. No explicit when-to-use conditions, no exclusions, and the sibling get_contact_options is never referenced despite contact data being mentioned in the description.

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