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

Annotations already mark the tool as read-only and non-destructive; the description adds valuable behavior beyond that: up to 10 results, result fields (id, title, url), the absence of contact details, and the instruction to direct users to the url. This is useful context, though pagination and ordering behavior are not addressed.

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 sentences with no filler: the tool's purpose, return shape, follow-up action, and a key caveat are all included. The most important information is front-loaded.

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 single-string-parameter, read-only search with no output schema, the description is complete: it covers how to phrase input, what the response contains, what to do next, and a critical exclusion (contact details). An agent has everything needed to select and invoke the tool correctly.

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 0%, so the description must carry the weight for the query parameter. It defines the parameter as a 'plain phrase' and gives a concrete example ('2 bedroom apartment in Son Tra under 15 million'), which effectively conveys the free-text nature. It could be slightly more explicit that the phrase maps directly to the query field, but the intent is obvious.

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 ('Search'), a clear resource ('long-term rentals in Da Nang'), and a concrete example of the input phrase. It is clearly distinct from fetch/get_listing, though it does not explicitly differentiate from the sibling search_listings, so it falls just short of a 5.

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?

Explains that the tool is meant for plain-phrase searches and tells the agent to pass an id to fetch for the full listing, which implies a natural follow-up action. It does not explicitly name when to prefer this over search_listings or market_stats, but the usage context is clear enough.

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