gmail_update_draft

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

Beyond the annotations, the description reveals a key behavioral trait: Gmail performs a full rewrite rather than a partial update, so callers must supply every field. This is exactly the kind of non-obvious behavior an agent needs to know to invoke the tool correctly and avoid silently resetting omitted fields.

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 concise and front-loaded: the central behavior and critical pitfall appear in the first two sentences, followed by a compact parameter list. There is no filler, and every line adds necessary information.

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 six-parameter mutation tool, the description provides enough behavioral and parameter context to call the tool correctly. It does not explicitly note that cc/bcc are optional or that null clears them, but the schema already marks those defaults. Output schema exists, so return-value documentation is not needed here.

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%, so the description carries the full burden of parameter explanation. It provides meaningful one-line meanings for all six parameters: draft_id, to, subject, body, cc, and bcc. It does not add format details like delimiter expectations, but the basic semantics are sufficient for correct use.

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 states the tool's action: 'Replace a draft's contents.' This distinguishes it from siblings like gmail_create_draft, gmail_delete_draft, and gmail_send_draft, which perform different operations on drafts. The scope is specific and immediately understandable.

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 gives clear context for the tool's intended use: modifying an existing draft. It also provides a critical operational guideline: because Gmail rewrites the entire message, all fields must be passed rather than only changed ones. It does not explicitly name alternatives or when-not-to-use cases, but the replacement semantics make the primary use case evident.

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