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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the agent knows this is a safe, closed-world lookup against a fixed service-area dataset. The description adds the useful domain constraint that the answer is scoped to one specific brokerage, but it does not state the return shape (boolean vs. matched area detail) or how partial/ambiguous inputs are handled. With annotations carrying the safety profile, a 3 is appropriate.

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 short sentences, zero filler, with the core question front-loaded. The interrogative phrasing is slightly indirect for a tool contract but costs no clarity or length.

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 one-parameter read-only lookup with full schema coverage and annotations, this is close to sufficient. The question form implicitly signals a yes/no answer, which partly compensates for the absent output schema; only the handling of ambiguous or out-of-scope inputs is left unstated.

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 single 'place' parameter is fully documented as 'A city and state, a ZIP code or an address.' The description largely repeats that list, with the only added detail being that a county is also accepted — which the schema does not mention, creating mild ambiguity about whether a bare county name is sufficient. Baseline 3 applies when the schema does the heavy lifting.

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 determination — whether London Foster Realty LLC serves a given place — which is a coverage lookup distinct from the siblings (about_brokerage, book_time, open_times, request_consultation). It is phrased as a question rather than a verb+resource statement, and the tool name 'check_area' alone would be vague, but the description resolves that.

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?

Usage is only implied: an agent can infer it should call this when a user asks whether the brokerage covers their location. The second sentence gives input format guidance ('Give a city, a county, a ZIP code or an address') but there is no explicit when-to-use/when-not framing and no reference to any sibling as an alternative.

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