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

With annotations already marking the tool read-only and idempotent, the description adds valuable behavioral detail: it uses only approved metadata, returns decision statuses, and explicitly does not prove savings or authorize purchases. This goes well beyond the annotations and clarifies the tool's operational boundaries.

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 focused sentences with no filler. The core purpose is front-loaded, then the return statuses, then the critical limitations and alternative. 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?

Given a complex 10-parameter schema with zero parameter descriptions and no output schema, the description provides a solid high-level frame but not enough to fully guide invocation or interpretation. It explains what the tool returns at a high level, but not how optional inputs influence the result or what the actual response shape is.

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 description coverage is 0%, and the description does not explain any of the 10 parameters or how they map to the stated outcomes. Terms like changed_parts_ppm, needs_shared_state, and local_alternative_available are left undefined, so the description fails to compensate for the schema's lack of descriptions.

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 names a specific action ('capability preflight') and clearly distinguishes it from content-reading or purchasing tools by stating 'no source content' and 'NEVER proves savings or authorizes a purchase.' It also lists the exact outcomes the tool can produce, making its role unambiguous among the mithrandir siblings.

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 an explicit alternative ('Use the local utility evaluator for complete-task cost evidence') and states what the tool cannot do, giving clear exclusion criteria. However, it does not explicitly define the positive condition for when to choose this tool over sibling tools, leaving 'preflight' to imply the use case.

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