OPA capabilities

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

Annotations already indicate readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds value by noting that full spec payload may exceed response size limits and explains the default behavior of 'names_only'. No contradictions.

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?

Three sentences covering purpose, parameter options, and a caveat about response size. No superfluous information. Well-structured and front-loaded with the main purpose.

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?

Despite lacking an output schema, the description adequately describes what is returned in different modes (list of versions, builtin names/count, full signatures). For a read-only, idempotent tool with strong annotations, this is complete and sufficient.

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 baseline is 3. The description adds explanatory context beyond schema descriptions, such as the mutual exclusivity of 'current' and 'version' and the reason for 'names_only' default (response size limits), thus enhancing understanding.

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 'Return OPA capabilities' and enumerates the contents (builtins, future keywords, features, WASM ABI versions). It differentiates behavior based on parameters and is distinct from sibling tools like rego_eval or rego_check, which serve different purposes.

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 explains when to use each parameter combination: 'current: true' for running OPA, 'version' for a specific version, neither for listing versions. It also clarifies the effect of 'names_only'. However, it does not explicitly state when not to use this tool or mention alternatives, though the context is clear.

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