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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds value beyond that by stating the return contract ('returns stored city IDs and location details') and reinforcing the non-mutating behavior, which matters because there is no output schema.

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 short sentences with zero filler: purpose/scope first, then the return payload, then the non-mutation caveat. Every sentence earns its place and the key constraint 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?

With no output schema, the description compensates by describing what comes back (city IDs and location details), and it covers purpose, usage stage, and side-effect posture. What remains unstated is matching behavior (exact vs. partial/alias ranking) and whether results are scoped to the user's saved data only, which keeps it from a 5.

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%: query length limits and the limit range/default are fully documented in the schema, and the description only restates 'city name or alias.' Per the baseline for fully covered schemas, this is a 3 – no extra syntax, matching, or ranking semantics are added.

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?

Names a specific verb ('Search') and resource ('the saved city catalog') and states the lookup keys (city name or alias). The 'saved catalog' scoping does implicitly distinguish it from open-ended siblings like places_search, but no sibling is named outright, so it stops 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?

'...before adding a city to a trip' gives the workflow stage where this tool belongs, and 'Search results do not add or select a city' draws the boundary against trip_city_add. There is clear context, but no explicit when-not-to-use or named alternative (e.g., places_search vs. this catalog search).

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