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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses additional behavioral details: it uses metered access (implying cost or rate limits) and specifies the output structure (ranked services, example endpoints, next step). This enriches the agent's understanding without contradicting the 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?

The description is succinct, covering purpose, usage, output, and caveats in three sentences without redundancy. It is well-structured, front-loading the core function and then adding usage guidance and alternative conditions.

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 schema (one parameter) and annotations (read-only, idempotent), the description completes the picture by explaining the return format, the metering aspect, and the decision tree for using this tool versus the sibling. No critical information is omitted for effective selection and invocation.

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 sole parameter 'capability' is described in the schema with examples, and the description reinforces this with additional examples and guidance on being concise. The parameter's purpose and expected value are fully explained, achieving complete 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 clearly states the tool's primary function: finding third-party APIs for a capability when the provider is unknown. It also differentiates from the sibling tool by explicitly instructing to use factreason_integration_brief when the provider is already known.

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 provides explicit conditions for when to use this tool ('when the provider is unknown') and when not to (calling the alternative when provider is known). It also gives a concrete example of a capability input ('send an SMS'), clarifying the expected parameter format.

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