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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds meaningful context beyond those: determinism, paid-resource cost ($0.002 USD per call), and the non-adjudication trust posture. No rate limits or auth details are provided, but the annotation coverage lowers the burden.

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?

Four short sentences, each earning its place: purpose, intended domain, prohibited uses, and cost. The description is front-loaded with the core behavior 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?

For a read-only, idempotent, two-parameter computation tool, the description covers purpose, parameter semantics, usage boundaries, and cost. The main missing piece is a concrete description of the output shape, which matters more because there is no output schema, but the rest is complete enough for confident 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?

Schema description coverage is 0%, so the description must compensate. It does translate both parameters semantically: 'observations' are caller-supplied observations and 'metric_fields' are explicitly named numeric fields. However, it omits details like how metric_fields map to observation keys or what statistics are produced, leaving notable gaps.

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 opening sentence states a specific action and scope: 'Computes deterministic descriptive benchmark statistics over caller-supplied observations and explicitly named numeric fields.' This distinguishes it from outcome-assurance or dispute-provenance feeds by positioning it for reliability quality / trust unknown, and it is not a tautology of the tool name.

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 intended use ('Intended for reliability quality / trust unknown') and strong negative guidance ('Do not use for legal, identity, sanctions, fraud, contractual, or regulatory adjudication'). It stops short of naming specific alternative sibling tools, so it earns a 4 rather than a 5.

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