unit_start_tool

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

With no annotations, the description must fully disclose behavior. 'Start a unit' only states the action but doesn't disclose side effects, error conditions, or whether the operation is reversible. It doesn't mention what happens if the unit is already started or what state changes occur. This is minimal and leaves critical behavioral details unaddressed, warranting a 2.

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 extremely concise (one sentence) and front-loaded, but it under-specifies. While brevity is good, it sacrifices necessary context. It is not verbose, but it also doesn't add enough value beyond the tool name, so a middle score of 3 is fair.

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 the presence of many sibling tools and the absence of annotations or output schema details, the description is insufficient. It doesn't explain when to use this over similar tools, nor what constitutes success or failure. The operation is simple, but with no guidance an agent might misuse it. It is not complete enough for effective tool selection.

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 schema provides 100% coverage with 'Systemd unit name' for the single parameter. The description adds no additional semantic meaning beyond the schema. Since schema already documents the parameter well, the baseline of 3 applies without any extra insight from the description.

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 'Start a unit' clearly specifies the verb (start) and the resource (unit). It is unambiguous about what it does, though it does not explicitly differentiate itself from sibling tools like unit_stop_tool or unit_restart_tool. It is a clear statement, so 4 is appropriate.

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 no guidance on when to use this tool versus the many alternatives (stop, restart, reload, etc.). It doesn't mention prerequisites, such as whether the unit must already be defined or enabled. Without any context or alternative comparisons, an agent receives no usage direction, so score is 2.

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