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

Annotations already declare non-read-only, idempotent, non-destructive; the description adds the parts annotations cannot: the false default, the human-consent prerequisite, the fact no mail is sent, and the distinction from an operator emergency flag. That is substantive behavioral context for a safety-sensitive toggle.

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?

Four short sentences, front-loaded with the effect and default before the safety caveat. Every sentence carries a distinct fact and none is 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?

For a two-parameter toggle with full schema coverage and annotations covering safety and idempotency, the description supplies what an agent needs to decide and call correctly. The only gap is response behavior on success or failure, which is minor here since no output schema exists and the call is a simple state set.

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 the schema already documents both booleans (including the const:true constraint). The description goes slightly beyond it by disclosing the current default state (sendEnabled defaults false), which frames what the call changes, though it adds nothing about the consent parameter beyond the schema.

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 effect on a specific resource: opting the account into or out of send_draft via the sendEnabled flag, and notes the default is false. It is clearly distinguishable from the actual sending sibling (send_draft) and from get_send_diagnostics.

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?

Gives an explicit gating condition ('Only call after the human clearly asks to turn sending on or off') plus two exclusions: it does not send mail, and it is separate from the operator-only emergency-send flag. Alternatives and when-not cases are both covered.

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