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

Annotations already mark the operation as read-only, idempotent, and non-destructive. The description adds meaningful behavioral guarantees beyond those annotations: it returns claims with sources and confidence, and explicitly states it 'never' returns an unsourced answer. No contradiction with annotations.

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 efficient sentences: the first states the action and output guarantee, the second provides routing guidance. Every sentence earns its place with 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?

With one well-described parameter, an output schema, clear annotations, and explicit sibling differentiation, the description is complete for an agent to select and invoke the tool correctly. No critical behavioral or usage detail 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% for the single parameter, so the baseline is 3. The description adds value by instructing the agent to use the question 'in the words the user asked it,' which preserves important original phrasing and prevents paraphrasing. This is useful semantic guidance beyond the schema.

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 action ('Answer a question from the corpus') and clearly specifies the output ('matched object's claims with sources and confidence'). It distinguishes itself from the 'search' sibling by positioning this as the direct-answer tool while search shows candidates.

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 when to use this tool ('when the user asked a question in words') and when to use the alternative ('use search when you want to see the candidates yourself'). This removes ambiguity about tool selection.

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