Batch-evaluate OPA policy against input files

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

Although annotations already declare readOnlyHint=true and idempotentHint=true, the description adds substantial behavior beyond that: per-file independent evaluation, error fields instead of result fields for failing files, CI-gate behavior reporting failed: true instead of erroring, and the decision-name normalization that prevents undefined results. No contradiction with annotations exists.

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 dense but every sentence earns its place: the core operation and tool name are front-loaded, the sibling comparison follows immediately, then per-file behavior, CI gates, and mutual exclusions are covered. The length is justified by the tool's complexity.

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 9-parameter tool with no output schema, the description covers invocation details, mutual exclusions, gate semantics, timeout bounds, and decision-name conversion. It could go slightly further by sketching the successful result envelope shape, but it adequately supports correct selection and 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 coverage is 100% and each parameter already has a solid description, so the baseline is 3. The description adds aggregate meaning by clarifying the interaction between fail/failDefined/failNonEmpty and the overall CI-gate result, plus the semantic difference between bundle and dataPaths. It adds value beyond the schema without replacing it.

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 opens with a specific verb and resource: 'Evaluate a policy decision against one or more input files using opa exec --format=json.' It immediately distinguishes itself from the sibling tool rego_eval by noting the single-input vs. batch-input difference, so an agent can tell them apart without inspecting schemas.

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?

It explicitly names rego_eval as the alternative for single inputs and says opa exec is 'ideal for CI pipelines that check many config files against a policy in one call.' It also explains when to use the fail gates and that bundle and dataPaths are mutually exclusive, giving clear selection and invocation guidance.

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