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

Annotations already cover read-only/open-world/non-destructive aspects. The description adds useful behavioral context: deterministic, stateless, keyless, offline, and bounded. It also discloses pricing and payment method ($0.05/call, x402), which informs operational usage. 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?

The description is compact at under three sentences, front-loaded with the primary verb and target. The pricing/payment adjunct is useful operational detail but arguably secondary; still, it does not feel verbose or redundant.

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 no output schema, the description compensates by listing the metric categories produced. It also clarifies stateless/offline constraints and pricing. It could be improved by explicitly defining 'warning' or 'digest' metrics or stating error behavior, but overall it provides sufficient context for an agent to select and invoke the tool correctly.

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 100%, so the parameter descriptions in the schema carry the burden. The tool description mentions 'rows you already collected' but adds no new semantic details about parameters like schemaVersion or the expected row structure, so the baseline of 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 action: 'Compute deterministic machine-friendly metrics' for 'US brand signal rows you already collected,' and enumerates metric categories (event, severity, status, source, confidence, warning, digest). This clearly identifies the tool's function and differentiates it from sibling tools focused on summaries, cross-tabs, or other transformations.

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 phrase 'rows you already collected' implies it is for post-collection processing, and 'bounded for agent pipelines' suggests a pipeline context. However, it does not explicitly state when not to use this tool or name alternative tools, leaving the agent to infer differentiation from sibling names.

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