Graph Mail MCP

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mail_update_draft

Update an existing email draft with new recipients, subject, body, or importance after validation, ensuring changes are applied only to drafts owned by the MCP server.

Instructions

Update an MCP-owned draft after registry and Graph preflight.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "draftId": "<draftId>",
      "patch": "<patch>"
    },
    "name": "mail_update_draft"
  }
}

Input Schema

Name	Required	Description	Default
`patch`	Yes
`draftId`	Yes
`expectedEtag`	No
`mailboxScope`	No
`expectedChangeKey`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 22, 2026

TDQS

B3/5.0

Behavior2/5

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

Annotations are absent, so the description must carry the behavioral burden. It mentions a preflight step implying some safety checks, but doesn't state whether the update requires draft ownership, whether it's reversible, or what the response is. For a mutation tool, this is lacking.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence, which is concise, but it's under-specified. It refers to 'registry and Graph preflight' that isn't elaborated, adding jargon without clarity, so it trades completeness for brevity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity (nested objects, 5 params, no output schema, no annotations), the description is insufficient. It doesn't explain the preflight conditions, the effect of expectedEtag, or what happens on conflict. An agent needs more to call this correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensateason. It doesn't explain the semantics of 'patch' or 'expectedEtag' or what the preflight checks. The description adds no information about parameters beyond the schema, leaving the agent to infer meaning from types and names.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the specific verb 'update' and resource 'an MCP-owned draft', distinguishing it from create draft and other mail tools. It also mentions a preflight step, but the phrase 'after registry and Graph preflight' is somewhat vague and doesn't fully clarify what the preflight entails.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies a workflow where preflight passes before updating, but doesn't give explicit when-to-use or when-not-to-use guidance. It doesn't compare to siblings like mail_create_draft or mail_get_message, so an agent has to infer usage from the name and context.

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

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