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

Annotations already flag destructive/openWorld/non-idempotent, but the description adds substantial context beyond them: exact fidelity of the send (same recipients, subject, text, attachments, threading onto the conversation), the once-only Sent filing, removal from Drafts, and the fact that this delivers real irreversible mail. This is the kind of disclosure an agent needs before calling a mutating tool.

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-loads the core action, then preconditions, then refusals, then the irreversibility warning. Four sentences, nearly all earning their place, though the 'as any mail client does' clause and the refusal enumeration push it slightly past the minimum needed.

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 one-parameter mutating tool with no output schema, the description covers action, preconditions, failure modes and irreversibility fully. Nothing an agent needs to invoke it correctly is missing.

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% and the single parameter already documents its source (list_pending_approvals), so the schema does the work. The description explains the draft's contents but adds no parsing or format detail about the uid itself; 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?

States a precise verb+resource ('Send a draft that a colleague marked with request_approval') and immediately differentiates itself from siblings like send_email and request_approval by scoping to already-approved drafts. An agent can tell exactly which operation this is 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?

Explicitly routes the agent: 'Read it first with read_email on the Drafts folder,' and the uid comes from list_pending_approvals. It also enumerates the when-not cases (not_pending, missing requester record, Bcc/Reply-To present) and notes each refusal explains remediation.

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