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

With no annotations, the description carries the full burden. It usefully discloses that this is a mutating operation and that it "Spends credit" (a cost signal), plus that it re-runs on the same cases/checks/models. It does not say whether the rewritten prompt replaces the original, whether the change is reversible, or what the call returns.

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?

Two tight sentences, front-loaded with the core action and ending on the cost warning, which is exactly the detail that should not be buried. No filler or restatement of the name.

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 tool is a credit-spending mutation with no output schema, so the description should hint at the result (new prompt, new scores, comparison?). It covers the action and cost well but leaves the return value and persistence semantics unaddressed.

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 0% for the single test_id parameter, so the description must compensate. It adds one meaningful constraint — the referenced test must be "finished" — but says nothing about identifier format or what happens if the test is unfinished.

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 pairs a specific verb ("Rewrite") with a specific resource ("a finished test's prompt") and adds the follow-up action of re-testing on the same cases, checks and models. It is clearly distinguishable from a plain test-runner like test_prompt, though it never names that sibling explicitly.

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?

"a finished test's" implies the precondition that the test must already be complete, which is useful gating. However, there is no explicit when-to-use vs when-not guidance and no named alternative (e.g., use test_prompt to evaluate without rewriting), so the agent must infer the routing.

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