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

Annotations already declare this is a non-read-only, non-destructive, closed-world mutation, so the safety profile is covered. The description adds that only unsent drafts are affected, but says nothing about whether the existing draft body is replaced or preserved, whether the instruction is bounded (the schema caps it at 500 chars), or any rate/cost behavior for what is presumably an AI generation call.

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?

A single tight sentence with the action and its two key constraints front-loaded and no filler. It is efficient, though it errs toward under-specification rather than maximal informativeness.

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 4-parameter mutation with no output schema, no parameter documentation and no sibling differentiation, the description leaves too much unresolved: what a successful call returns, whether the prior draft text is overwritten, and what each ID refers to.

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 description coverage is 0% across 4 required parameters, so the schema gives no meaning at all. The description only alludes to 'instruction'; projectId, siteId and threadId are entirely unexplained, and no format or example for the instruction is offered.

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+resource ('Rewrite ... draft') and adds two useful qualifiers: the draft must be 'unsent' and the rewrite follows an 'instruction'. That is enough to distinguish it from create_outreach_draft, but it never names or contrasts update_outreach_draft, the closest sibling.

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 word 'unsent' implies a precondition (an existing draft that has not been sent), which is mild guidance, but there is no explicit when-to-use statement and no routing against update_outreach_draft or prepare_outreach_draft.

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