derive

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

Despite readOnlyHint=true already covering safety, the description adds 'deterministic' and 'unsupported/unknown findings,' which disclose output behavior beyond the annotation. It also clarifies the partial scope beyond any annotation info.

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 extremely concise, using only two sentences to convey purpose, scope, and input requirements. Every phrase adds value 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?

For a single-parameter read-only tool with an output schema, the description covers the necessary context: what it does, its scope, and input format. The output schema handles return value details, so the description is complete for its complexity.

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?

Input schema already describes 'ref' as a DDB URL or id at 100% coverage, but the description adds 'exact public' as a constraint not present in the schema. This extra semantic detail helps the agent understand acceptable inputs.

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 compiles selected character fields into specific outputs (deterministic values, trust states, provenance, lint). It includes a scoping note about partial read-only context, which differentiates it from full rules validation, though it does not explicitly distinguish from sibling tools.

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 implies usage context by stating 'partial read-only context, not complete rules validation,' suggesting it is for lighter checks rather than full validation. It does not explicitly name alternatives or state when-not-to-use, so guidance is implied rather than explicit.

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