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

Beyond the annotations, the description explicitly states that this tool "writes a message and delivers it," clarifying that it has real side effects and sends an actual email. It also discloses the optional status mutation, which is not fully implied by readOnlyHint=false.

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 sentences with no filler; the primary action is front-loaded and the side-effect warning is concise. Every clause contributes to selection or invocation understanding.

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?

The description covers the core purpose, the side effects, and the optional status behavior. It does not state return values or explicitly warn about non-idempotency, but the annotations and simple parameter set make the tool adequately callable.

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 only 33%, but the description adds meaning for status by specifying that it can be set to in_progress or done, and for text by framing it as the content of the reply. It does not explicitly explain the text parameter format or that task_id comes from cooper_get_tasks, though the schema covers the latter.

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 action: "Send an in-thread email back to the human who created the task." It also mentions the optional status update, making the tool's combined behavior clear. This differentiates it from generic siblings like cooper_send_message.

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 when to use it: when replying in-thread to the task creator. However, it does not explicitly contrast it with alternatives such as cooper_send_message or cooper_notify_owner, so an agent must infer the selection boundary.

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