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

Even though annotations already declare readOnlyHint, idempotentHint, and destructiveHint/false, the description adds meaningful behavioral context beyond annotations: it returns claims with sources and confidence, and it never returns an unsourced answer. This clarifies the tool's output policy and constraints, which is valuable for an agent deciding whether the result is trustworthy.

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 two sentences with no filler. The primary behavior is front-loaded, the output guarantee is concise, and the usage contrast with search is efficient. Every sentence earns its place.

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 tool with a full output schema and safety annotations, the description covers what the tool does, when to use it, what it returns, and how it differs from the main alternative. Nothing critical is missing for correct invocation by 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?

Schema coverage is 100% and the single parameter is already described in the input schema as "The question to answer, in the words the user asked it." The tool description reinforces the verbatim aspect but does not add substantial new meaning beyond the schema, so baseline 3 is appropriate.

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 verb and resource: "Answer a question from the corpus" and clearly describes the output as matched claims with sources and confidence. It also distinguishes itself from the sibling tool search by naming the exact contrast, so an agent can tell them apart without opening other schemas.

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?

Explicit usage guidance is provided: "Use this when the user asked a question in words; use search when you want to see the candidates yourself." This gives both a positive condition and an explicit alternative, leaving no ambiguity about when to invoke this tool.

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