Evaluate Rego with coverage

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, indicating the tool is safe and non-destructive. The description adds that it returns per-line coverage data, which is helpful but does not disclose any additional behavioral traits like performance impact or error handling.

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 consists of two concise sentences. The first explains the core functionality, and the second gives a practical use case. No unnecessary words 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?

The description adequately explains the tool's purpose and output format but lacks detail on when to choose this over similar tools (e.g., rego_eval or rego_test). With no output schema, the description could be more specific about the structure of the coverage data, but overall it is sufficient for basic understanding.

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?

All 8 parameters have descriptions in the input schema (100% coverage). The tool description does not add any further parameter semantics, so the baseline score 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 clearly states 'Evaluate with --coverage and return per-line coverage data', which specifies the action and output. It distinguishes from siblings like rego_eval by emphasizing coverage, but does not explicitly differentiate from rego_eval_with_explain or rego_eval_with_profile.

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 a use case: 'Useful for verifying that tests actually exercise the rules they're meant to.' However, it does not specify when not to use this tool, nor does it mention alternatives like rego_eval or rego_test.

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