MCP Tools Reference: firebasedataconnect.googleapis.com

Tool: execute_graphql_read

Executes a read-only GraphQL query against a Firebase SQL Connect Service instance.

Grants read access to the connected data sources. Identical to execute_graphql except it only accepts read-only queries.

When to use it:

  • Use this tool to execute read-only GraphQL queries (fetching records, filtering, listing data).

How to use it:

  • Call execute_graphql_read with projectId, location, serviceId to identify the service, and provide the GraphQL query string.
  • Optionally provide variables, operationName, and extensions.

JSON Example:

{
          "projectId": "my-project",
          "location": "us-central1",
          "serviceId": "my-service",
          "query": "query GetUser($id: UUID!) { user(id: $id) { name } }",
          "variables": {
            "id": "123e4567-e89b-12d3-a456-426614174000"
          }
        }

The following code sample shows how to use curl to call the execute_graphql_read MCP tool.

Curl Request 
curl --location 'https://firebasedataconnect.googleapis.com/mcp' \
--header 'content-type: application/json' \
--header 'accept: application/json, text/event-stream' \
--data '{
  "method": "tools/call",
  "params": {
    "name": "execute_graphql_read",
    "arguments": {
      // provide these details according to the tool's MCP specification
    }
  },
  "jsonrpc": "2.0",
  "id": 1
}'

Input Schema

Request message for ExecuteGraphql facade.

ExecuteGraphqlRequest

JSON representation 
{
  "projectId": string,
  "location": string,
  "serviceId": string,
  "query": string,
  "variables": {
    object
  },
  "extensions": {
    object (GraphqlRequestExtensions)
  },

  // Union field _operation_name can be only one of the following:
  "operationName": string
  // End of list of possible types for union field _operation_name.
}
Fields
projectId

string

Required. The project ID or number.
location

string

Required. The location of the service.
serviceId

string

Required. Identifier. The service ID.
query

string

Required. The GraphQL query document source.
variables

object (Struct format)

Optional. Values for GraphQL variables provided in this request.
extensions

object (GraphqlRequestExtensions)

Optional. Additional GraphQL request information.

Union field _operation_name.

_operation_name can be only one of the following:
operationName

string

Optional. The name of the GraphQL operation name.

Struct

JSON representation 
{
  "fields": {
    string: value,
    ...
  }
}
Fields
fields

map (key: string, value: value (Value format))

Unordered map of dynamically typed values.

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.

FieldsEntry

JSON representation 
{
  "key": string,
  "value": value
}
Fields
key

string
value

value (Value format)

Value

JSON representation 
{

  // Union field kind can be only one of the following:
  "nullValue": null,
  "numberValue": number,
  "stringValue": string,
  "boolValue": boolean,
  "structValue": {
    object
  },
  "listValue": array
  // End of list of possible types for union field kind.
}
Fields
Union field kind. The kind of value. kind can be only one of the following:
nullValue

null

Represents a JSON null.
numberValue

number

Represents a JSON number. Must not be NaN, Infinity or -Infinity, since those are not supported in JSON. This also cannot represent large Int64 values, since JSON format generally does not support them in its number type.
stringValue

string

Represents a JSON string.
boolValue

boolean

Represents a JSON boolean (true or false literal in JSON).
structValue

object (Struct format)

Represents a JSON object.
listValue

array (ListValue format)

Represents a JSON array.

ListValue

JSON representation 
{
  "values": [
    value
  ]
}
Fields
values[]

value (Value format)

Repeated field of dynamically typed values.

GraphqlRequestExtensions

JSON representation 
{
  "impersonate": {
    object (Impersonation)
  }
}
Fields
impersonate

object (Impersonation)

Optional. If set, impersonate a request with given Firebase Auth context and evaluate the auth policies on the operation. If omitted, bypass any defined auth policies.

Impersonation

JSON representation 
{
  "includeDebugDetails": boolean,

  // Union field kind can be only one of the following:
  "unauthenticated": boolean,
  "authClaims": {
    object
  }
  // End of list of possible types for union field kind.
}
Fields
includeDebugDetails

boolean

Optional. If set, include debug details in GraphQL error extensions.
Union field kind. The kind of impersonation. kind can be only one of the following:
unauthenticated

boolean

Evaluate the auth policy as an unauthenticated request. Can only be set to true.
authClaims

object (Struct format)

Evaluate the auth policy with a customized JWT auth token. Should follow the Firebase Auth token format. https://firebase.google.com/docs/rules/rules-and-auth

For example: a verified user may have auth_claims of {"sub": , "email_verified": true}

NullValue

Represents a JSON null.

NullValue is a sentinel, using an enum with only one value to represent the null value for the Value type union.

A field of type NullValue with any value other than 0 is considered invalid. Most ProtoJSON serializers will emit a Value with a null_value set as a JSON null regardless of the integer value, and so will round trip to a 0 value.

Enums
NULL_VALUE Null value.

Output Schema

The GraphQL response from Firebase SQL Connect.

It strives to match the GraphQL over HTTP spec. Note: Firebase SQL Connect always responds with Content-Type: application/json. https://github.com/graphql/graphql-over-http/blob/main/spec/GraphQLOverHTTP.md#body

GraphqlResponse

JSON representation 
{
  "data": {
    object
  },
  "errors": [
    {
      object (GraphqlError)
    }
  ],
  "extensions": {
    object (GraphqlResponseExtensions)
  }
}
Fields
data

object (Struct format)

The result of the execution of the requested operation. If an error was raised before execution begins, the data entry should not be present in the result. (a request error: https://spec.graphql.org/draft/#sec-Errors.Request-Errors) If an error was raised during the execution that prevented a valid response, the data entry in the response should be null. (a field error: https://spec.graphql.org/draft/#sec-Errors.Error-Result-Format)
errors[]

object (GraphqlError)

Errors of this response. If the data entry in the response is not present, the errors entry must be present. It conforms to https://spec.graphql.org/draft/#sec-Errors .
extensions

object (GraphqlResponseExtensions)

Additional response information. It conforms to https://spec.graphql.org/draft/#sec-Extensions .

Struct

JSON representation 
{
  "fields": {
    string: value,
    ...
  }
}
Fields
fields

map (key: string, value: value (Value format))

Unordered map of dynamically typed values.

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.

FieldsEntry

JSON representation 
{
  "key": string,
  "value": value
}
Fields
key

string
value

value (Value format)

Value

JSON representation 
{

  // Union field kind can be only one of the following:
  "nullValue": null,
  "numberValue": number,
  "stringValue": string,
  "boolValue": boolean,
  "structValue": {
    object
  },
  "listValue": array
  // End of list of possible types for union field kind.
}
Fields
Union field kind. The kind of value. kind can be only one of the following:
nullValue

null

Represents a JSON null.
numberValue

number

Represents a JSON number. Must not be NaN, Infinity or -Infinity, since those are not supported in JSON. This also cannot represent large Int64 values, since JSON format generally does not support them in its number type.
stringValue

string

Represents a JSON string.
boolValue

boolean

Represents a JSON boolean (true or false literal in JSON).
structValue

object (Struct format)

Represents a JSON object.
listValue

array (ListValue format)

Represents a JSON array.

ListValue

JSON representation 
{
  "values": [
    value
  ]
}
Fields
values[]

value (Value format)

Repeated field of dynamically typed values.

GraphqlError

JSON representation 
{
  "message": string,
  "locations": [
    {
      object (SourceLocation)
    }
  ],
  "path": array,
  "extensions": {
    object (GraphqlErrorExtensions)
  }
}
Fields
message

string

The detailed error message. The message should help developer understand the underlying problem without leaking internal data.
locations[]

object (SourceLocation)

The source locations where the error occurred. Locations should help developers and toolings identify the source of error quickly.

Included in admin endpoints (ExecuteGraphql, ExecuteGraphqlRead, IntrospectGraphql, ImpersonateQuery, ImpersonateMutation, UpdateSchema and UpdateConnector) to reference the provided GraphQL GQL document.

Omitted in ExecuteMutation and ExecuteQuery since the caller shouldn't have access access the underlying GQL source.
path

array (ListValue format)

The result field which could not be populated due to error.

Clients can use path to identify whether a null result is intentional or caused by a runtime error. It should be a list of string or index from the root of GraphQL query document.
extensions

object (GraphqlErrorExtensions)

Additional error information.

SourceLocation

JSON representation 
{
  "line": integer,
  "column": integer
}
Fields
line

integer

Line number starting at 1.
column

integer

Column number starting at 1.

GraphqlErrorExtensions

JSON representation 
{
  "file": string,
  "code": enum (Code),
  "debugDetails": string,
  "warningLevel": enum (WarningLevel),
  "workarounds": [
    {
      object (Workaround)
    }
  ]
}
Fields
file

string

The source file name where the error occurred. Included only for UpdateSchema and UpdateConnector, it corresponds to File.path of the provided Source.
code

enum (Code)

Maps to canonical gRPC codes. If not specified, it represents Code.INTERNAL.
debugDetails

string

More detailed error message to assist debugging. It contains application business logic that are inappropriate to leak publicly.

In the emulator, SQL Connect API always includes it to assist local development and debugging. In the backend, ConnectorService always hides it. GraphqlService without impersonation always include it. GraphqlService with impersonation includes it only if explicitly opted-in with include_debug_details in GraphqlRequestExtensions.
warningLevel

enum (WarningLevel)

Warning level describes the severity and required action to suppress this warning when Firebase CLI run into it.
workarounds[]

object (Workaround)

Workarounds provide suggestions to address the compile errors or warnings.

Workaround

JSON representation 
{
  "description": string,
  "reason": string,
  "replace": string
}
Fields
description

string

Description of this workaround.
reason

string

Why would this workaround address the error and warning.
replace

string

A suggested code snippet to fix the error and warning.

GraphqlResponseExtensions

JSON representation 
{
  "dataConnect": [
    {
      object (DataConnectProperties)
    }
  ]
}
Fields
dataConnect[]

object (DataConnectProperties)

SQL Connect specific GraphQL extension, a list of paths and properties.

DataConnectProperties

JSON representation 
{
  "path": array,
  "entityId": string,
  "entityIds": [
    string
  ],
  "maxAge": string
}
Fields
path

array (ListValue format)

The path under response.data where the rest of the fields apply. Each element may be a string (field name) or number (array index). The root of response.data is denoted by the empty list [].
entityId

string

A single Entity ID. Set if the path points to a single entity.
entityIds[]

string

A list of Entity IDs. Set if the path points to an array of entities. An ID is present for each element of the array at the corresponding index.
maxAge

string (Duration format)

The server-suggested duration before data under path is considered stale.

A duration in seconds with up to nine fractional digits, ending with 's'. Example: "3.5s".

Duration

JSON representation 
{
  "seconds": string,
  "nanos": integer
}
Fields
seconds

string (int64 format)

Signed seconds of the span of time. Must be from -315,576,000,000 to +315,576,000,000 inclusive. Note: these bounds are computed from: 60 sec/min * 60 min/hr * 24 hr/day * 365.25 days/year * 10000 years
nanos

integer

Signed fractions of a second at nanosecond resolution of the span of time. Durations less than one second are represented with a 0 seconds field and a positive or negative nanos field. For durations of one second or more, a non-zero value for the nanos field must be of the same sign as the seconds field. Must be from -999,999,999 to +999,999,999 inclusive.

NullValue

Represents a JSON null.

NullValue is a sentinel, using an enum with only one value to represent the null value for the Value type union.

A field of type NullValue with any value other than 0 is considered invalid. Most ProtoJSON serializers will emit a Value with a null_value set as a JSON null regardless of the integer value, and so will round trip to a 0 value.

Enums
NULL_VALUE Null value.

Code

The canonical error codes for gRPC APIs.

Sometimes multiple error codes may apply. Services should return the most specific error code that applies. For example, prefer OUT_OF_RANGE over FAILED_PRECONDITION if both codes apply. Similarly prefer NOT_FOUND or ALREADY_EXISTS over FAILED_PRECONDITION.

Enums
OK

Not an error; returned on success.

HTTP Mapping: 200 OK
CANCELLED

The operation was cancelled, typically by the caller.

HTTP Mapping: 499 Client Closed Request
UNKNOWN

Unknown error. For example, this error may be returned when a Status value received from another address space belongs to an error space that is not known in this address space. Also errors raised by APIs that do not return enough error information may be converted to this error.

HTTP Mapping: 500 Internal Server Error
INVALID_ARGUMENT

The client specified an invalid argument. Note that this differs from FAILED_PRECONDITION. INVALID_ARGUMENT indicates arguments that are problematic regardless of the state of the system (e.g., a malformed file name).

HTTP Mapping: 400 Bad Request
DEADLINE_EXCEEDED

The deadline expired before the operation could complete. For operations that change the state of the system, this error may be returned even if the operation has completed successfully. For example, a successful response from a server could have been delayed long enough for the deadline to expire.

HTTP Mapping: 504 Gateway Timeout
NOT_FOUND

Some requested entity (e.g., file or directory) was not found.

Note to server developers: if a request is denied for an entire class of users, such as gradual feature rollout or undocumented allowlist, NOT_FOUND may be used. If a request is denied for some users within a class of users, such as user-based access control, PERMISSION_DENIED must be used.

HTTP Mapping: 404 Not Found
ALREADY_EXISTS

The entity that a client attempted to create (e.g., file or directory) already exists.

HTTP Mapping: 409 Conflict
PERMISSION_DENIED

The caller does not have permission to execute the specified operation. PERMISSION_DENIED must not be used for rejections caused by exhausting some resource (use RESOURCE_EXHAUSTED instead for those errors). PERMISSION_DENIED must not be used if the caller can not be identified (use UNAUTHENTICATED instead for those errors). This error code does not imply the request is valid or the requested entity exists or satisfies other pre-conditions.

HTTP Mapping: 403 Forbidden
UNAUTHENTICATED

The request does not have valid authentication credentials for the operation.

HTTP Mapping: 401 Unauthorized
RESOURCE_EXHAUSTED

Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space.

HTTP Mapping: 429 Too Many Requests
FAILED_PRECONDITION

The operation was rejected because the system is not in a state required for the operation's execution. For example, the directory to be deleted is non-empty, an rmdir operation is applied to a non-directory, etc.

Service implementors can use the following guidelines to decide between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE: (a) Use UNAVAILABLE if the client can retry just the failing call. (b) Use ABORTED if the client should retry at a higher level. For example, when a client-specified test-and-set fails, indicating the client should restart a read-modify-write sequence. (c) Use FAILED_PRECONDITION if the client should not retry until the system state has been explicitly fixed. For example, if an "rmdir" fails because the directory is non-empty, FAILED_PRECONDITION should be returned since the client should not retry unless the files are deleted from the directory.

HTTP Mapping: 400 Bad Request
ABORTED

The operation was aborted, typically due to a concurrency issue such as a sequencer check failure or transaction abort.

See the guidelines above for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.

HTTP Mapping: 409 Conflict
OUT_OF_RANGE

The operation was attempted past the valid range. E.g., seeking or reading past end-of-file.

Unlike INVALID_ARGUMENT, this error indicates a problem that may be fixed if the system state changes. For example, a 32-bit file system will generate INVALID_ARGUMENT if asked to read at an offset that is not in the range [0,2^32-1], but it will generate OUT_OF_RANGE if asked to read from an offset past the current file size.

There is a fair bit of overlap between FAILED_PRECONDITION and OUT_OF_RANGE. We recommend using OUT_OF_RANGE (the more specific error) when it applies so that callers who are iterating through a space can easily look for an OUT_OF_RANGE error to detect when they are done.

HTTP Mapping: 400 Bad Request
UNIMPLEMENTED

The operation is not implemented or is not supported/enabled in this service.

HTTP Mapping: 501 Not Implemented
INTERNAL

Internal errors. This means that some invariants expected by the underlying system have been broken. This error code is reserved for serious errors.

HTTP Mapping: 500 Internal Server Error
UNAVAILABLE

The service is currently unavailable. This is most likely a transient condition, which can be corrected by retrying with a backoff. Note that it is not always safe to retry non-idempotent operations.

See the guidelines above for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.

HTTP Mapping: 503 Service Unavailable
DATA_LOSS

Unrecoverable data loss or corruption.

HTTP Mapping: 500 Internal Server Error

WarningLevel

WarningLevel describes the severity and required action to suppress this warning when Firebase CLI run into it.

Enums
WARNING_LEVEL_UNKNOWN Warning level is not specified.
LOG_ONLY Display a warning without action needed.
INTERACTIVE_ACK Request a confirmation in interactive deployment flow.
REQUIRE_ACK Require an explicit confirmation in all deployment flows.
REQUIRE_FORCE Require --force in all deployment flows.

Tool Annotations

Tool annotations are sent to MCP clients to describe the basic risk of a given tool. Most clients treat these hints as untrusted, but they can be used to decide when a confirmation prompt might be sent to a user.

Along with the title string, the following boolean hints are defined as follows:

  • readOnlyHint: If true, the tool doesn't modify its environment. Default: false.
  • destructiveHint: If true, then the tool can perform destructive actions. If false, then the tool can only perform additive actions. Default: true.
  • idempotentHint: If true, then calling the tool repeatedly with the same arguments will have no additional effect on its environment. Default: false.
  • openWorldHint: If true, then the tool can interact with an 'open world' of external entities. If false, then the tool can only interact with internal entities. For example, a web search tool would be open world, while a memory tool would not be open world.

Destructive Hint: ❌ | Idempotent Hint: ✅ | Read Only Hint: ✅ | Open World Hint: ❌