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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint), so the bar is lower but the description still adds substantial behavioral context: the API-key/rate-limit model ('works without an API key up to a daily per-IP allowance... a free API key raises the allowance') and important data semantics ('location.city is whatever tier the listing was filed under'). These are genuinely useful and go well beyond structured fields.

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?

Three front-loaded paragraphs, each earning its place: core purpose and usage, operational/auth constraints, and a data-quality caveat. There is no fluff, and the most important invocation-relevant information appears first.

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 2-parameter read-only tool with an output schema and strong annotations, the description covers everything needed: what it returns, when to call it, how auth works, where to route alternative intents, and how to interpret a subtle field (`location.city` vs `location.municipality`). 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 50%: `reference` is documented in the schema and the description reinforces it with the 'human-readable id' framing. However, the description adds nothing about the `language` parameter, leaving its semantics to the self-explanatory enum and default. The description adds marginal value over the schema for `reference` and no value for `language`, so it sits at the acceptable baseline.

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: 'Fetch the full record for one PropertyList listing by its reference code.' It also distinguishes itself from siblings by naming search_properties and find_properties_by_description as the preceding search tools and submit_enquiry as the contact-related alternative. An agent knows exactly what this tool is for.

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?

Explicit usage guidance: 'Use this once the user has settled on a listing from search_properties or find_properties_by_description and wants details or photos.' It also provides an explicit alternative for a different intent: 'To contact the listing agency, use submit_enquiry.' The when and when-not conditions are unambiguous.

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