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

With no annotations, the description carries the burden well: it discloses the staff-only restriction, the side effect of flagging the row, and that a later send record clears the flag. It stops short of saying whether re-saving overwrites an existing draft or what the tool returns, so it is strong but not exhaustive.

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 staff-only constraint and the core action, then layers guidance. The bolded 'You cannot send anything' and the closing rationale are slightly repetitive, but nearly every sentence adds operative detail 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?

For a mutation tool with no annotations and no output schema, this covers the essential context: who may call it, what it changes, and which sibling to use instead. Only the return value/confirmation shape is left unstated.

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 baseline is 3, but the description adds real semantics for `draft` beyond the schema ('write the message itself, not a description of one — no placeholders'). It adds nothing extra for `needs_action_reason`, which the schema already documents including its default.

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 and resource ('Save an opener against a prospect'), names the consumer (Elliot) and the side effect (flags the row as waiting on him). An agent can separate this from record-prospect-outreach-tool because the description explicitly says 'Recording the send later clears both.'

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?

Explicit when-to-use and when-not-to-use: write here if you can produce an honest opener, otherwise use `update-prospect` to park the row with the question. It also states the division of labour (you research/write, he sends) so the agent knows this tool never sends.

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