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

Annotations already declare readOnly/idempotent/openWorld=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it is the entry-point call whose output feeds location_id into downstream calls, and it specifies the correct response when no city matches.

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, front-loaded with the purpose and positioned as the first call in the workflow. Every sentence carries actionable information with no filler.

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 optional-parameter lookup with an output schema and full annotation coverage, the description provides everything needed: what it returns conceptually (location_id), when to call it, and the no-match handling.

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% and the name parameter (partial city match, omit for full list) is fully documented in the schema. The description adds no parameter-level detail beyond that, so baseline 3 applies.

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: lists the cities where Lab4U tests are available. The resource (cities/locations) is clearly distinct from the sibling tools (basket, cart link, test details, test search), though it does not explicitly name them.

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?

Gives explicit usage guidance: 'Вызывай первым' (call this first) to obtain the user's location_id, plus a fallback instruction when the city is absent. No alternatives are named, but the sibling tools are different resources, so routing is unambiguous.

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