Gmail MCP

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create_forwarding_address

Set up email forwarding in Gmail by creating a forwarding address to automatically redirect incoming messages to another email account.

Instructions

Creates a forwarding address

Input Schema

TableJSON Schema

Name	Required	Description	Default
`forwardingEmail`	Yes	An email address to which messages can be forwarded

Implementation Reference

src/index.ts:1044-1055 (registration)

Registration of the create_forwarding_address tool on the MCP server, including schema and inline handler implementation.

server.tool("create_forwarding_address",
  "Creates a forwarding address",
  {
    forwardingEmail: z.string().describe("An email address to which messages can be forwarded")
  },
  async (params) => {
    return handleTool(config, async (gmail: gmail_v1.Gmail) => {
      const { data } = await gmail.users.settings.forwardingAddresses.create({ userId: 'me', requestBody: params })
      return formatResponse(data)
    })
  }
)

src/index.ts:1049-1054 (handler)

Handler executes the tool logic by calling Gmail API's users.settings.forwardingAddresses.create via the shared handleTool wrapper.

async (params) => {
  return handleTool(config, async (gmail: gmail_v1.Gmail) => {
    const { data } = await gmail.users.settings.forwardingAddresses.create({ userId: 'me', requestBody: params })
    return formatResponse(data)
  })
}

src/index.ts:1046-1048 (schema)

Zod schema defining the input parameter forwardingEmail.

{
  forwardingEmail: z.string().describe("An email address to which messages can be forwarded")
},

src/index.ts:49-65 (helper)

Shared helper function handleTool that sets up OAuth2 client, validates credentials, creates Gmail client, and executes the API call.

const handleTool = async (queryConfig: Record<string, any> | undefined, apiCall: (gmail: gmail_v1.Gmail) => Promise<any>) => {
  try {
    const oauth2Client = queryConfig ? createOAuth2Client(queryConfig) : defaultOAuth2Client
    if (!oauth2Client) throw new Error('OAuth2 client could not be created, please check your credentials')

    const credentialsAreValid = await validateCredentials(oauth2Client)
    if (!credentialsAreValid) throw new Error('OAuth2 credentials are invalid, please re-authenticate')

    const gmailClient = queryConfig ? google.gmail({ version: 'v1', auth: oauth2Client }) : defaultGmailClient
    if (!gmailClient) throw new Error('Gmail client could not be created, please check your credentials')

    const result = await apiCall(gmailClient)
    return result
  } catch (error: any) {
    return `Tool execution failed: ${error.message}`
  }
}

src/index.ts:47-47 (helper)

Helper function to format API responses for MCP tool output.

const formatResponse = (response: any) => ({ content: [{ type: "text", text: JSON.stringify(response) }] })

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.0.0Jan 4, 2026
- addedInput schema / $schema
```
Added value: +"http://json-schema.org/draft-07/schema#"
```
- addedInput schema / additionalProperties
```
Added value: +false
```
First observedNov 18, 2025

TDQS

B3.2/5.0

Behavior2/5

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

No annotations exist, and the description only says 'Creates', implying mutation but not disclosing behavioral traits such as whether it triggers a verification email, duplicates handling, or return value.

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?

One sentence, front-loaded, with no wasted words; however, it could be more informative without being longer.

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

Completeness3/5

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

For a simple create tool with one parameter and no output schema, the description is sufficient for basic understanding but lacks context on side effects or related processes like verification.

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 coverage is 100%, so the schema already describes the single parameter; the description adds no additional meaning beyond the verb.

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 the action 'Creates' and the resource 'forwarding address', which distinguishes it from siblings like 'delete_forwarding_address' and 'list_forwarding_addresses'.

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?

The description provides no guidance on when to use this tool vs alternatives, or any prerequisites like authentication or existing address verification.

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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