evaluate_terraform_policies

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

Annotations already carry readOnly/idempotent/non-destructive/closed-world, so the lower bar applies; the description still adds real context the annotations don't: an OPA dependency, a directory allow-list restriction, and that returned findings deliberately exclude resource attribute values. It stops short of describing cost, rate limits, or failure modes on an invalid plan file.

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 tight sentences with the core action and target front-loaded and zero filler. The sentence about return contents is slightly redundant given an output schema exists, but it carries a real caveat about withheld attribute values.

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?

With a full output schema and rich annotations, the description covers the operational envelope (OPA required, directory restriction, no live infrastructure access) well. The one material gap is that policy selection behavior is left entirely to the schema's top-level note, so an agent reading only the description would not know how to scope which policies run.

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 0% for the two parameters, so the description must compensate and largely does not. 'plan_path' is only obliquely implied by 'a local Terraform plan JSON file in an allowed directory'; 'policy_ids' (array, max 4, with non-obvious omission-vs-null semantics) is never mentioned in the description at all.

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?

States a specific verb (evaluate), specific resource (bundled governance policies) and a specific target (a local Terraform plan JSON file in an allowed directory). This is clearly distinguishable from analyze_terraform_plan (plan analysis) and list_policies (enumeration) without opening either schema.

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?

Establishes the preconditions for use: the plan must already be a local JSON file in an allowed directory and OPA must be configured. It also carves out the boundary ('does not inspect or modify deployed infrastructure'), but never names analyze_terraform_plan or list_policies as alternatives or states when to prefer them.

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