tarn_last_failures

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

Discloses that it reads a persisted file rather than re-running tests, implying non-destructive behavior and efficiency. No annotations provided, so description carries the burden well.

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 sentences, front-loaded with purpose, no wasted words. Efficient and clear.

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?

No output schema is provided, but the description specifies 'structured JSON' which is adequate for a utility tool. Could detail the JSON structure more, but context from sibling tools and schema covers essential needs.

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%, so baseline score is 3. Description does not add additional parameter details beyond what the schema already provides.

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?

Clearly states it returns grouped failures for a specific run as structured JSON, distinguishing itself from sibling tools like tarn_report by noting it provides a failures-only view without loading the full report.

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?

Provides explicit usage context: 'Useful for agents that want a failures-only view without loading the full report.' Does not explicitly list alternatives or when not to use, but the guidance is sufficient.

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