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

With no annotations, the description carries the behavioral burden and covers metering, wallet debiting, the exact surcharge formula, and response fields source_tier/tier_label. It does not explicitly state whether the call is read-only, but the GET verb and query semantics make that largely inferable.

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?

The description is dense but every clause adds necessary information for a metered call, and the purpose is front-loaded. The final sentence about source_tier/tier_label is terse but important, so the length is justified rather than padded.

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?

Because there is no output schema and no annotations, the description must explain both inputs and behavior; it does so for all parameters, the billing model, and some response metadata. It stops short of enumerating the full response shape or entity_type allowed values, but it provides enough to invoke the tool correctly.

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?

The schema has 0% description coverage, yet the description names and explains all six parameters: lat/lng required, radius_km default, entity_type optional, limit cap and default, include_country_centroids default. It adds constraints and units that the raw JSON schema does not provide.

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 opens with 'Entities near a location (the primitive look_from builds on)' and defines the endpoint as GET /nearby with typed query params, so it is immediately clear that this tool returns entities within a radius. It also distinguishes itself from the sibling look_from by labeling itself as the primitive that tool builds on.

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?

The description gives no explicit when-to-use or when-not-to-use guidance against alternatives like look_from. However, it does provide process guidance: check the caller's own wallet with the joules_balance tool and get an exact price with billing_quote before calling, which tells an agent what to do before invoking it.

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