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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds the 'today/week' scoping of the returned focus minutes, which is a useful behavioral detail about what time range the stats cover. It does not disclose how streak is computed or whether the response shape is a summary object, but given annotation coverage, a 3 is appropriate.

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 a short, front-loaded list of returned data with no filler words. It is concise but is a sentence fragment lacking a verb, so it is not as polished as a fully structured sentence. Still, every word earns its place.

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 zero-parameter, read-only stats endpoint with a clear annotation profile, the description is largely complete: it names the metrics returned. The lack of an output schema is partially offset by the list of data points. It does not give units or date format details, but for this simple tool that is a minor gap.

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 tool has zero parameters, so there are no input semantics for the description to explain. Per the rubric baseline, 0 parameters earns a 4. No further parameter information is needed.

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 title 'Focus Statistics' and the description make it clear that this tool returns focus-related metrics. The description enumerates the specific data points (focus minutes, streak, completion rates), which distinguishes it from sibling tools like get_tasks or get_journal. However, it lacks an explicit verb such as 'retrieves' or 'returns', so it falls short of a purpose statement that names the action.

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 provides no guidance on when to use this tool versus alternatives. It doesn't state what types of queries are appropriate or reference any sibling tools. The only hint is the name and content, which implies this is the default for focus stats, but no explicit usage context or exclusions are given.

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