list_services

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

Annotations already declare this a safe, idempotent, closed-world read, so the bar is lower. The description still adds real context beyond them: it discloses that both system and user units are included, that user units are tagged '(user)', and what attributes each row carries. It says nothing about pagination behavior beyond the schema's own limit note.

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 dense sentence with the resource front-loaded, followed by the returned attributes and then the filtering capability. No filler, no repetition; the parenthetical '(user)' marker is a genuinely load-bearing detail.

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?

With no output schema, the description carries the burden of describing return values and does so adequately by listing the per-service attributes. Combined with the full schema coverage of inputs and the read-only annotations, an agent has what it needs to call this correctly; only the sibling-routing question remains open.

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 all three parameters (limit, state, filter) are fully documented in the schema, establishing a baseline of 3. The description's 'Filter by text and state' restates the schema rather than adding format, matching rules, or edge-case behavior.

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 names a specific resource (systemd services) and enumerates the returned fields (unit name, description, state, startup type, process), so an agent knows exactly what it gets. It does not explicitly distinguish itself from the singular sibling get_service or from list_startup_items, leaving that distinction to inference.

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 only implied: the phrase 'Filter by text and state' suggests a browsing/inspection use case, but there is no statement of when to choose this over get_service (single unit detail) or list_startup_items. No exclusions or prerequisites are given.

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