tarn_rerun_failed

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. While it states what the tool does, it does not discuss side effects (e.g., whether it triggers test execution, writes files), permissions, or read-only nature. This is insufficient for a tool that likely performs write operations.

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 two sentences, both front-loaded with the core action and followed by valuable context about the response shape. No unnecessary words, every sentence earns its place.

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?

Given 5 parameters, no output schema, and nested objects, the description is relatively brief. It explains the core purpose and return shape but does not detail how 'failing pairs' are determined, error cases, or prerequisites (e.g., a prior run must exist). Adequate but with clear gaps.

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?

Input schema coverage is 100%, so the parameters are well documented in the schema. The description adds some context about the return shape but does not add meaning beyond what the schema provides for the parameters themselves. Baseline 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 that the tool reruns only failing (file, test) pairs from a prior run, using the verb 'rerun' and specifying the resource. It distinguishes from siblings like tarn_run (which runs all tests) and tarn_run_agent (different purpose).

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 clear context by mentioning that the response shape matches tarn_run, enabling a loop of run → inspect → rerun without switching tool surfaces. However, it lacks explicit when-not or alternative tool guidance.

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