Mutation Configuration

By default, only GraphQL queries are exposed as MCP tools. Mutations are opt-in because they modify data and AI agents should not accidentally trigger destructive operations.

Mutation Modes

There are three mutation exposure modes:

none (default)

Only queries are converted to tools. Mutations are ignored entirely.

CLI:

graphql2mcp https://api.example.com/graphql
# or explicitly:
graphql2mcp https://api.example.com/graphql -m none

Library:

registerGraphQLTools(server, {
    source: './schema.graphql',
    endpoint: 'https://api.example.com/graphql',
    mutations: 'none'
});

Core:

const { tools } = generateTools({
    schema,
    mutations: 'none'
});

all

All queries and all mutations are converted to tools.

CLI:

graphql2mcp https://api.example.com/graphql -m all

Library:

registerGraphQLTools(server, {
    source: './schema.graphql',
    endpoint: 'https://api.example.com/graphql',
    mutations: 'all'
});

Core:

const { tools } = generateTools({
    schema,
    mutations: 'all'
});

whitelist

Only the named mutations are converted to tools. All queries are still included.

CLI:

graphql2mcp https://api.example.com/graphql \
  -m whitelist \
  --mutation-whitelist createUser updateUser

Library:

registerGraphQLTools(server, {
    source: './schema.graphql',
    endpoint: 'https://api.example.com/graphql',
    mutations: { whitelist: ['createUser', 'updateUser'] }
});

Core:

const { tools } = generateTools({
    schema,
    mutations: { whitelist: ['createUser', 'updateUser'] }
});

Whitelisted names that do not match any mutation in the schema are silently ignored. This makes it safe to specify mutations that may not exist in all schema versions.

Tool Annotations

MCP tool annotations communicate the nature of each tool to AI agents and clients. graphql2mcp sets these automatically based on the operation type.

Query annotations

{
    readOnlyHint: true,
    destructiveHint: false,
    openWorldHint: true
}

Queries are marked as read-only and non-destructive. This signals to AI agents that calling a query tool is safe and does not modify any data.

Mutation annotations

{
    readOnlyHint: false,
    destructiveHint: true,
    openWorldHint: true
}

Mutations are marked as non-read-only and potentially destructive. MCP clients may use this to require user confirmation before executing mutation tools.

Combining with Include/Exclude Filters

Mutation mode works alongside the include and exclude filters. Exclude takes precedence over include.

// Only expose these specific queries and mutations
registerGraphQLTools(server, {
    source: './schema.graphql',
    endpoint: 'https://api.example.com/graphql',
    mutations: 'all',
    include: ['users', 'user', 'createUser'],
    exclude: ['deleteUser']
});

# Expose all mutations except deleteUser and dropDatabase
graphql2mcp https://api.example.com/graphql \
  -m all \
  --exclude deleteUser dropDatabase

Recommended Approach

For production deployments, use whitelist mode. This provides explicit control over which mutations are available to AI agents:

registerGraphQLTools(server, {
    source: './schema.graphql',
    endpoint: 'https://api.example.com/graphql',
    mutations: {
        whitelist: [
            'createUser',
            'updateUser',
            'createPost'
            // deleteUser intentionally omitted
        ]
    }
});

This is safer than all because new mutations added to the schema do not automatically become available to AI agents.