service_state

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

With no annotations, the description carries the full burden and does so well: it explicitly declares read-only behavior ('never changes state'), names the exact read commands executed, and describes the returned JSON shape. It omits auth/permission requirements and any rate or cost characteristics, which is the remaining gap for a zero-annotation tool.

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?

Three dense sentences, front-loaded with the resource and scope, followed by the read-only guarantee and the return contract. No filler or repetition; every clause carries information an agent can act on.

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?

There is no output schema, and the description compensates by spelling out the return object ({units: [{unit, enabled, active, needs_reload}]}) and the semantics of each field's purpose. Combined with the read-only disclosure and the single required input, an agent has everything needed to call and interpret it.

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?

Only one parameter and schema description coverage is 100%, so the schema already explains the '<account>/<name>' and 'custom/<name>' forms. The description adds no parameter detail beyond the schema, 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?

States a specific resource and scope: the enablement/active/reload state of one instance's enabled systemd services, with the underlying commands (systemctl is-enabled/is-active, NeedDaemonReload) named. This cleanly separates it from siblings like docker_ps (containers), journal_errors (logs), or check_status (general health), so an agent can pick it without opening the schema.

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?

Usage is implied rather than stated: 'Powers the service-state detector (enabled-but-inactive, needs-reload, active-but-unnecessary)' tells the agent the situations it answers, but no sibling is named as an alternative and there is no explicit when-not-to-use guidance. Adequate context, but routing is left to inference.

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