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modify_message

Add or remove labels from Gmail messages to organize your inbox by categorizing emails with specific tags for better email management.

Instructions

Modify the labels on a message

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
idYesThe ID of the message to modify
addLabelIdsNoA list of label IDs to add to the message
removeLabelIdsNoA list of label IDs to remove from the message

Implementation Reference

  • src/index.ts:611-624 (registration)
    Registration of the 'modify_message' tool, including description, input schema, and handler function.
    server.tool("modify_message",
      "Modify the labels on a message",
      {
        id: z.string().describe("The ID of the message to modify"),
        addLabelIds: z.array(z.string()).optional().describe("A list of label IDs to add to the message"),
        removeLabelIds: z.array(z.string()).optional().describe("A list of label IDs to remove from the message")
      },
      async (params) => {
        return handleTool(config, async (gmail: gmail_v1.Gmail) => {
          const { data } = await gmail.users.messages.modify({ userId: 'me', id: params.id, requestBody: { addLabelIds: params.addLabelIds, removeLabelIds: params.removeLabelIds } })
          return formatResponse(data)
        })
      }
    )
  • Zod schema defining input parameters for the modify_message tool: message ID and optional label IDs to add/remove.
    {
      id: z.string().describe("The ID of the message to modify"),
      addLabelIds: z.array(z.string()).optional().describe("A list of label IDs to add to the message"),
      removeLabelIds: z.array(z.string()).optional().describe("A list of label IDs to remove from the message")
    },
  • Handler implementation that uses handleTool to authenticate and call Gmail API's users.messages.modify to update message labels.
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.messages.modify({ userId: 'me', id: params.id, requestBody: { addLabelIds: params.addLabelIds, removeLabelIds: params.removeLabelIds } })
        return formatResponse(data)
      })
    }

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

B3.1/5.0
Behavior2/5

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

No annotations are provided, and the description only says 'modify the labels' without detailing behavior for conflicting add/remove, invalid IDs, or return values.

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

Conciseness4/5

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

A single sentence that is concise and front-loaded, but could be expanded slightly for completeness without losing efficiency.

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?

Lack of output schema and annotations, plus no description of return values or error handling, makes it incomplete for a simple mutation tool.

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 100%, providing clear parameter descriptions. The description adds no extra meaning beyond the schema, meeting the baseline.

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

Purpose5/5

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

The description clearly states that the tool modifies labels on a message, distinguishing it from siblings like batch_modify_messages and modify_thread.

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

Usage Guidelines2/5

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

There is no guidance on when to use this tool vs. alternatives (e.g., batch_modify_messages for multiple messages) or prerequisites like label existence.

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