coverage_for

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

With no annotations provided, the description carries the full burden of explaining the tool's behavior. It clearly states that the tool is a read-only query ('Ask... Returns...'), enumerates what the response includes, and adds context for interpreting results (thin vs. well-evidenced). It does not mention permissions or side effects, but for a non-mutating coverage tool, this is sufficient.

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 three sentences, each earning its place: the first states the purpose and timing, the second details the return values, and the third gives usage guidance. It is front-loaded with the key intent and contains no filler or repetition.

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?

Given the tool's simplicity (one parameter, no output schema), the description is nearly complete. It explains what the tool does, when to use it, and what it returns. It could optionally mention the response format in more detail, but the enumerated return components (claim count, operators, sweeps) make the tool comprehensible for an agent.

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 already provides 100% coverage for the single parameter 'subject' with a description. The tool description does not add significant extra meaning beyond referring to 'a subject' in the first sentence, so it matches the baseline of 3 for high schema coverage.

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 directly states the tool's function: asking how well-evidenced a subject is, and enumerates the specific outputs (number of claims, distinct operators, and sweeps). This clearly distinguishes it from siblings like search_claims (which retrieves claims) and corpus_stats (which provides overall statistics).

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 explicit guidance on when to use the tool: 'Call this first on any question where being wrong is expensive.' It also instructs the agent to 'relay a thin result rather than answering around it,' telling it how to act on the output. However, it does not explicitly mention when not to use it or name alternatives, so it stops short of a full 5.

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