Apollo Connectors Schema Assistant

MCP Tools

If GraphOS MCP Tools are available, use them:

• connectors-spec: Fetch the complete Connectors specification before starting any connector work

• apollo_docs_search: Search for relevant documentation

• apollo_docs_read: Read specific documentation pages by slug

Documentation paths by topic:

• Requests: /graphos/connectors/requests/url, /headers, /body, /batching

• Responses: /graphos/connectors/responses/fields, /error-handling

• Mapping: /graphos/connectors/mapping, /arrays, /enums, /literals

• Entities: /graphos/connectors/entities, /patterns

Process

Follow this 5-step process. DO NOT skip any steps.

Step 1: Research

• Understand the API being called and the structure of responses

• Ask the user for example API responses if not provided

• Fetch relevant documentation from MCP tools or reference files

• DO NOT write any code until research is complete

Step 2: Implement

• Create the schema using the template below

• Follow the grammar, methods, and variables in the reference files

• Ask clarifying questions if unsure about requirements

Step 3: Validate (Compose)

• Run rover supergraph compose --config ./supergraph.yaml

• Fix any composition errors before proceeding

Step 4: Execute

• Run rover connector run --schema <file> -c "<Type.field>" -v "{}"

• Verify the connector executes correctly

Step 5: Test

• Create or update test files under /tests/

• Run rover connector test

• Ensure full test coverage for each connector

Schema Template

# Note to AI Friends: This is an Apollo Connectors schema. You should use your connectors-spec MCP tool if you have it available before editing this file.

extend schema

  @link(url: "https://specs.apollo.dev/federation/v2.12")

  @link(url: "https://specs.apollo.dev/connect/v0.3", import: ["@source", "@connect"])

@source(name: "api_name", http: { baseURL: "https://api.example.com" })

type Query {

  example(id: ID!): Example

    @connect(

      source: "api_name"

      http: { GET: "/example/{$args.id}" }

      selection: """

      id

      name

      """

    )

}

type Example {

  id: ID!

  name: String

}

Version Requirements: Always use federation/v2.12 and connect/v0.3 unless specified otherwise.

Reference Files

Before implementing connectors, read the relevant reference files:

• Grammar - Selection mapping EBNF syntax

• Methods - Available transformation methods

• Variables - Available mapping variables

• Entities - Entity patterns and batching

• Validation - Rover commands for validation

• Troubleshooting - Common errors and solutions

Key Rules

Selection Mapping

• Prefer sub-selections over ->map for cleaner mappings

• Do NOT use $ when selecting fields directly from root

• Field aliasing: newName: originalField (only when renaming)

• Sub-selection: fieldName { ... } (to map nested content)

# DO - Direct sub-selection for arrays

$.results {

  firstName: name.first

  lastName: name.last

}

# DO NOT - Unnecessary root $

$ {

  id

  name

}

# DO - Direct field selection

id

name

Entities

• Add @connect on a type to make it an entity (no @key needed)

• Create entity stubs in parent selections: user: { id: userId }

• When you see an ID field (e.g., productId), create an entity relationship

• Each entity should have ONE authoritative subgraph with @connect

Literal Values

Use $() wrapper for literal values in mappings:

$(1)              # number

$(true)           # boolean

$("hello")        # string

$({"a": "b"})     # object

# In body

body: "$({ a: $args.a })"  # CORRECT

body: "{ a: $args.a }"     # WRONG - will not compose

Headers

http: {

  GET: "/api"

  headers: [

    { name: "Authorization", value: "Bearer {$env.API_KEY}" },

    { name: "X-Forwarded", from: "x-client" }

  ]

}

Batching

Convert N+1 patterns using $batch:

type Product @connect(

  source: "api"

  http: {

    POST: "/batch"

    body: "ids: $batch.id"

  }

  selection: "id name"

) {

  id: ID!

  name: String

}

Ground Rules

• NEVER make up syntax or directive values not in this specification

• NEVER use --elv2-license accept (for humans only)

• ALWAYS ask for example API responses before writing code

• ALWAYS validate with rover supergraph compose after changes

• ALWAYS create entity relationships when you see ID fields

• Prefer $env over $config for environment variables

• Use rover dev for running Apollo Router locally