control_focus_session

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

Annotations already declare non-read-only, non-idempotent, non-destructive behavior, but the description adds meaningful context beyond them: starting replaces the current timer and retries should not be blind. It also notes that completion respects existing notification preferences. It does not contradict 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?

The description is short and front-loaded with purpose. Each sentence adds relevant context, though 'Completion uses existing notification preferences' is slightly tangential compared to the more actionable replacement and retry warnings.

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 timer tool with annotations and no output schema, the description covers the main behavioral risks: replacement on start, notification preference behavior, and retry caution. The main gap is that it says nothing about the duration parameter, but the schema supplies its name and default.

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 0%, so the description must compensate. It clarifies the meaning of 'start' as replacing the current timer and 'cancel' as stopping the timer, but it does not explain the optional 'minutes' parameter or its 25-minute default, leaving part of the schema undocumented in prose.

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 states a specific verb and resource: start/replace or cancel the dashboard focus timer. It clearly distinguishes the two actions and is specific enough that an agent can tell what the tool does 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 usage through the start/cancel actions and adds a useful caution ('do not retry blindly'), but it does not explicitly say when to use this tool instead of the sibling get_focus_session or list prerequisites. Usage is mostly implied rather than fully guided.

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