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

Annotations declare destructiveHint=true, which might otherwise suggest existing data is wiped; the description usefully clarifies the opposite — the change applies only to time logged from then on and already-logged entries keep their setting. It also discloses the required editor-role permission, adding context beyond the annotations.

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 tight sentences, front-loaded with the core action, followed by scope of effect and prerequisite. No filler or redundancy.

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?

For a simple two-parameter mutation with annotations covering the safety profile and no output schema, the description supplies the value semantics, the temporal scope of the change, and the permission requirement. Only minor gaps remain (e.g., behavior on a nonexistent or closed task).

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 only 50% (cardId has no description), but the description fully explains the semantics of the undocumented-in-schema state space for 'billable' — true/false meaning and null meaning 'follow the project's default' — which goes beyond the schema's single-line note.

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 (sets) and resource (billable status of time logged on a task) and enumerates the three possible states. An agent can distinguish this from neighbors like set_task_visible_to_client or set_task_field 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?

The description implies the context (toggling billing behavior on a task) and gives one prerequisite ('Needs the editor role on the project'), but never states when to prefer this over alternatives such as setting billability at the project or time-entry level. Usage 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.