grpc_call
Call a unary gRPC method using JSON input. Supports server reflection or local .proto files.
LABSCO SUMMARY
Reflection is offered, not assumed, and that is what makes this usable against services you do not control.
Both tools accept either path: use_reflection asks the server to describe itself, while proto_files and import_paths cover a target that has reflection turned off, which production services frequently do. The scope is deliberately narrow — grpc_call is documented for unary methods, so streaming is not what this is for. Within that scope the pairing is complete: grpc_describe tells you the message shape, grpc_call sends one built to match, and headers, plaintext and timeout_ms handle the parts of a real connection that a schema does not describe.
What it is
A gRPC client exposing 2 tools: one that describes services, methods and message symbols, and one that invokes a unary method from a JSON request body.
What you get
- Discovery before invocation: grpc_describe resolves a service, a method or a message symbol so the request shape is known before anything is sent.
- Calls written as JSON: grpc_call takes request_json and a fully qualified method, returning the response without any generated stub in between.
- Either source of schema: both tools work from server reflection with use_reflection, or from local proto_files resolved against import_paths.
- The connection details a real target needs: headers carries whatever metadata the service authenticates on, plaintext covers a target without TLS, and timeout_ms bounds the call.
Requirements
Nothing to configure for the server itself. Reaching a target needs either reflection enabled on it or the .proto files and their import paths present on the machine the server runs on, plus whatever credential that service expects, which travels in headers rather than in configuration.
Setup effort
One command — npx -y @grulex/grpc-invoke-mcp@latest
USE CASES
01
Calling a gRPC method without generating a client
Resolve the method and its request message from the target, then send a JSON body built to match it.
02
Working against a service that has reflection turned off
Point the tools at the .proto files and their import paths instead of the server, and describe and call exactly as you would otherwise.
2 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
grpc_describe
Describe gRPC services, methods, or message symbols using server reflection or local .proto files.
BEFORE YOU INSTALL
What to know first
Tools you get
2 tools when we connected.
Requires
npx on PATH
CONTEXT COST
Light Standing cost
Rated by the size of the 2 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Add the block to your client, or run the command directly.
Server setup
Configuration file
JSON
{
"mcpServers": {
"grpc-invoke-mcp": {
"command": "npx",
"args": [
"-y",
"@grulex/grpc-invoke-mcp@latest"
]
}
}
}npx
TERMINAL
npx -y @grulex/grpc-invoke-mcp@latest
