Start an add-on

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

Annotations cover the safety profile (readOnly=false, destructive=false), and the description adds genuinely new behavioral context: the HTTP endpoint, the SUPERVISOR_TOKEN prerequisite, and three distinct error payloads including invalid slug and token-missing conditions. The 'already running' error is in mild tension with idempotentHint=true, but this is a hint-level nuance rather than a contradiction.

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?

Front-loads the action, then uses labeled Use when / Not for / Returns / Errors sections. Each line carries distinct information (routing, prerequisite, error taxonomy) with no filler.

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 exists, so return values need not be detailed, yet the description still notes the start-job result. Combined with the error catalogue and auth prerequisite, an agent has everything needed to invoke this correctly and handle failures.

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% and the schema's slug description already explains the format and points to supervisor_list_addons. The description adds nothing beyond flagging a possible 'invalid_slug' error, so the baseline 3 for schema-covered parameters is appropriate.

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+resource+state transition ('Start an installed, stopped add-on') and even names the underlying endpoint. It explicitly distinguishes itself from supervisor_install_addon and supervisor_stop_addon, so an agent can select it without opening sibling schemas.

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?

Contains explicit 'Use when' and 'Not for' clauses, each routing to the correct alternative tool (supervisor_install_addon for installing, supervisor_stop_addon for stopping). Nothing 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.