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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantive context beyond them: requires auth, the wait parameter's long-poll behavior (returns as soon as a task arrives), and a security policy about treating task text as untrusted data. That last item is genuinely valuable behavioral guidance not captured anywhere in structured fields.

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 usage trigger and resource scope, then parameters, then return shape, then a safety caveat. It is dense but every sentence carries information; the parenthetical parameter and field lists add some bulk but are useful rather than filler.

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?

No output schema exists, and the description compensates by listing the returned fields (id, inbox_id, status, sender, subject, text, quoted_text, verified_owner, trusted, auth, created_at). Combined with the auth requirement, long-poll semantics, and untrusted-data policy, an agent has everything needed to call and interpret this tool correctly.

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 baseline is 3, but the description adds real meaning: inbox_id omission means 'all inboxes', status defaults to pending, and wait is described as long-poll seconds that return early when a task arrives. These are semantic clarifications beyond the schema's terse parameter descriptions.

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 (lists) and resource (tasks) plus the precise scope: tasks created when a verified owner or allowlisted sender emails the inbox and the mail passes DMARC/DKIM. This scope statement clearly distinguishes it from siblings like cooper_list_messages and cooper_get_message without needing to open their schemas.

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 opening clause gives a concrete trigger condition: 'Use this when you are waiting for a human's instructions or answer by email.' That is a clear when-to-use signal. It stops short of naming an alternative tool or stating when not to use it, so it does not reach a 5.

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