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

Annotations already declare it is a write (readOnlyHint=false) and non-destructive. The description adds genuinely behavioral context beyond that: no lease/worker identity is required, and comments surface in the task's activity timeline and the web UI, which tells the agent the side effect and visibility. It stops short of auth/rate-limit detail, so not a 5.

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-loaded with the core action, then the sibling contrast, then the visibility note. Three tight sentences with no waste; the trailing API reference URL is minor padding but harmless.

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 write tool with annotations covering the safety profile and no output schema needed, the description covers purpose, alternative, and where the result appears. It omits auth requirements beyond the lease point and any rate-limit note, which keeps it from a 5.

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%, so both parameters (task_id accepting an id or URL, body supporting @handle mentions) are already documented in the schema. The description adds no parameter-level meaning beyond that, so the baseline 3 applies.

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?

Specific verb ('leave a comment') and resource ('on a task'), with the scope made concrete ('plain comment ... for your teammates'). It explicitly names and contrasts with the sibling add_progress_note, so an agent can distinguish it without opening either 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?

States when to use it ('questions, context, and notes to whoever picks the task up next') and names the alternative (add_progress_note) plus the selecting condition (no lease or worker identity needed). This is explicit routing guidance, not inference.

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