Start a focus session

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

No annotations are present, so the description carries the full burden. It discloses the cross-device takeover behavior, the one-active-session rule, and the default length. It does not state what happens to the preempted session or describe the response shape, but the most consequential behaviors are covered.

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?

Two dense sentences with no filler. The default behavior is front-loaded, and the warning about existing sessions earns its place because it directly affects invocation strategy.

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 tool with no output schema, the description covers defaults, constraints, preconditions, and the correct sibling alternative. It does not describe the return value, which would be useful with no output schema, but this omission does not prevent correct selection or invocation.

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?

The schema describes task_id but leaves minutes undocumented. The description compensates by explaining the default pomodoro length and the 1-to-240 minute range, which clarifies behavior when minutes is omitted. Task_id is already well covered by the schema description.

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 ('Start') and resource ('server-side focus session'), and immediately clarifies the one-active-session-per-account constraint. This clearly distinguishes it from siblings like dwt_switch_task and dwt_log_session.

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?

Explicitly instructs the agent to call dwt_status first and prefer dwt_switch_task when a session is already running. It also provides the default duration context, giving clear when-to-use and when-not-to-use guidance.

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