Unit List Tool

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

readOnlyHint=true already tells the agent this is a safe read, so the annotation carries the safety profile. The description adds no behavioral context of its own — nothing about ordering, result volume, pagination, or how the default active/failed filtering behaves, which is the sort of nuance annotations do not cover.

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?

A single four-word sentence, front-loaded and free of waste. It is efficient but borders on under-specification rather than being genuinely well-structured for a tool with meaningful filtering options.

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?

An output schema and annotations cover return shape and safety, but the description leaves the core selection problem unsolved: with siblings like failed_units_tool and timer_list_tool, an agent needs at least a hint about scope (all units vs. failed vs. timers). That routing context is entirely missing.

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 description coverage is 100%; all three parameters (mode, pattern, all_units) are documented with defaults and examples in the schema itself. The description adds no additional parameter meaning, so the baseline 3 applies.

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?

"List systemd units" states a clear verb (list) and resource (systemd units), so the basic operation is unambiguous. However, it makes no attempt to distinguish this from siblings like failed_units_tool, timer_list_tool, or unit_status_tool, which an agent must disambiguate among.

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?

There is no when-to-use guidance, no mention of alternatives, and no exclusions. With 20 sibling tools including failed_units_tool and timer_list_tool, the agent gets no signal about why to pick this general lister over the specialized ones.

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