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

Annotations cover the safety profile (write, non-idempotent, non-destructive, closed-world), so the bar is lower. The description adds real value beyond them: it discloses that buildings are appended to the renter's persistent saved list and that the return is a shareable /my-list?s=... URL with compare/AI Read/tour features. It doesn't warn about duplicate entries on repeat calls despite idempotentHint=false.

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?

Two sentences, front-loaded with the core action and output, followed by the critical naming constraint. Slightly padded by the feature list ('compare, AI Read, and free tour requests'), which is marketing color rather than calling guidance.

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?

An output schema exists, so the return value needn't be explained, and the description still usefully characterizes the returned link. It covers the write effect (buildings added to a saved list) and input sourcing; only edge cases like duplicate handling or the 10-item cap (already in schema) are left implicit.

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 schema fully documents all three parameters, making 3 the baseline. The description's 'Use the EXACT names returned by search_apartments' reinforces the apartment_names semantics but largely restates the schema's own wording, adding no new syntax or format detail.

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 names a specific action (turn finalist apartments into a shareable link) and a specific resource (Taco Street shortlist at /my-list), and explicitly ties it to the sibling search_apartments as its input source. An agent can distinguish this from search_apartments and get_apartment_details without opening schemas.

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?

'Turn finalist apartments into...' clearly implies this is the post-search step, used once a renter has narrowed candidates, and tells the agent to pull names from search_apartments. It gives a clear usage context but states no exclusions, no limit/duplication caveats, and no explicit when-not-to-use guidance.

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