update_draft

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

Annotations already indicate destructiveness (destructiveHint: true). The description adds context beyond annotations by specifying that the draft must be 'MCP-created' and that there is no send capability. This provides useful behavioral constraints without contradicting the annotations.

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 extremely concise, consisting of two short sentences. Every word adds value: 'Replace one MCP-created draft' states the action and scope, and 'the broker has no send capability' adds a critical limitation. No fluff or repetition.

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 the tool's complexity (8 parameters, a destructive write operation, and sibling tools), the description is under-specified. It leaves ambiguity around the 'MCP-created' restriction and provides no information on parameter behavior or what happens to existing data. The presence of an output schema does not compensate for missing operational context.

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?

The input schema has 8 parameters with 0% description coverage, and the description does not mention any of them. It fails to clarify whether parameters like cc, bcc, or attachment_names are optional, how they interact, or whether replacement is partial or full. The description adds no meaning beyond the schema's titles.

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 function: 'Replace one MCP-created draft.' This uses a specific verb ('replace') and a specific resource ('draft'), distinguishing it from sibling create_draft. It also adds context that the tool does not send, further clarifying its purpose.

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 implies usage: it replaces an existing draft, and the note 'the broker has no send capability' hints that this is not for sending. However, it does not explicitly mention when to use this tool versus alternatives like create_draft or set_star. The guidance is implied rather than explicit.

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