Failed Units Tool

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

The readOnlyHint annotation already tells the agent this is a safe read, so the description's remaining job is small. The only added detail is the return shape (units plus count), which largely duplicates the existing output schema; nothing is said about empty-state behavior or ordering.

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 short lines, with the purpose front-loaded and the return detail after it. Every sentence carries information, and no filler is present.

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?

This is a simple, parameterless read tool with annotations and an output schema, so its description covers the essentials plus a triage cue. The only minor gap is the absence of guidance on what to do next when the list is empty or non-empty.

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?

The tool takes zero parameters, so there is nothing for the description to document; the baseline for a parameterless tool is 4. The schema is also fully closed (additionalProperties: false), leaving no ambiguity.

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 (list) and a precisely scoped resource (units currently in the 'failed' state), which is more targeted than the generic unit_list_tool. It never names a sibling explicitly, so the differentiation is implicit rather than spelled out.

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 first thing to check at 2AM' hints at a triage use case, giving some usage context. However, there is no explicit when-not condition and no pointer to alternatives such as unit_status_tool or journal_query_tool for follow-up diagnosis.

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