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

readOnlyHint=true already signals a safe read, so the bar is lower, and the description adds what the agent actually gets back (gym counts, drop-in counts, open-mat counts). It says nothing about result volume or default-limit behavior, but the return-shape disclosure is genuinely useful given 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?

Two sentences with no waste: the first defines the payload, the second defines the usage and the sibling relationship. Front-loaded with the resource and its contents.

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 three-param read-only lookup with no output schema, the description covers resource, payload fields, filtering, and the call-ordering relationship to find_gyms. Nothing an agent needs in order to select and call it correctly is missing.

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 q, limit, and state are already documented in the schema, which sets the baseline at 3. The description restates the city-name and two-letter-state filters but adds no format or syntax detail beyond what the schema provides, and omits limit entirely.

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 and resource (lists US cities OpenMapp covers) plus the exact payload contents: gym counts, drop-in-welcoming gym counts, and open-mat listings. This distinguishes it from find_gyms, which returns gyms rather than coverage.

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?

Explicitly tells the agent to use it to check coverage before calling find_gyms, naming the sibling alternative and the ordering condition. It stops short of stating when-not to use it, but the routing intent is unambiguous.

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