update_draft

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

The description goes far beyond the annotations by revealing the delete-and-recreate implementation, the return of a NEW draft_id, preservation of threading metadata, attachment merge semantics, and performance caveats. Annotations only flag idempotent/destructive/read-only status; the description provides the operational detail needed to avoid surprising side effects. No contradiction with annotations exists.

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?

The description is longer than average but each sentence carries essential information about behavior, edge cases, and performance. The delete-and-recreate fact is front-loaded, and bolded sections for return value and merge semantics aid scanning. Some verbosity around seed recovery could be trimmed, but it is all relevant to correct invocation.

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?

Given 12 parameters, destructive semantics, and complexity, the description is remarkably complete. It covers return value, field merge rules, attachment handling, body_html caveats, external-draft performance, and a forward-seed misclassification warning. The only minor gap is template behavior, but that is likely documented in create_draft, which is referenced. An agent has enough context to invoke safely.

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?

With 58% schema description coverage, the description adds valuable global merge semantics: any non-None argument overrides, None preserves, and attachment_paths has special behavior for None, [], and a list. It also clarifies the non-obvious body_html limitation (must be re-passed or lost). This compensates well for parameters like template_name and template_vars that the schema leaves undocumented.

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?

The description clearly identifies the operation as updating an existing draft, and immediately adds the crucial implementation detail that it is delete-and-recreate. This distinguishes it from create_draft and delete_draft, though the name alone could mislead until the description is read. The verb+resource+behavior is specific enough for an agent to know what the tool does.

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 description explains when to use this tool: when a saved draft needs mutation, since Mail.app forbids direct editing. It gives guidance for externally-created drafts, warning about slow In-Reply-To scanning and recommending an explicit body for forward seeds. It does not explicitly name sibling alternatives, but the context makes the appropriate usage clear.

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