PatchworkMCP - Rust

Drop-in feedback tool for Rust MCP servers. Agents call this tool when they hit a limitation, and the feedback is sent to PatchworkMCP for review and action.

Setup

1. Go to patchworkmcp.com and create an account
2. Create a team and generate an API key
3. Configure your server (you'll need the server slug and API key)

Install

Add to your Cargo.toml:

reqwest = { version = "0.12", features = ["json"] }
serde = { version = "1", features = ["derive"] }
serde_json = "1"
tokio = { version = "1", features = ["full"] }

Then copy src/lib.rs into your project (or add as a dependency).

Configure

Set these environment variables (or pass them via Options):

Usage

use patchworkmcp::{payload_from_args, send_feedback};

// Build payload from MCP call_tool arguments:
let payload = payload_from_args(&args, None);

// Send feedback:
let message = send_feedback(&payload, None).await;

With options

use patchworkmcp::{Options, payload_from_args, send_feedback};

let opts = Options {
    patchwork_url: Some("https://custom.example.com".to_string()),
    api_key: Some("my-key".to_string()),
    server_slug: Some("my-server".to_string()),
};

let payload = payload_from_args(&args, Some(&opts));
let message = send_feedback(&payload, Some(&opts)).await;

Tool registration

use patchworkmcp::{TOOL_NAME, TOOL_DESCRIPTION, tool_input_schema};

// Register with your MCP framework:
let schema = tool_input_schema();

Server Instructions

When initializing your MCP server, set the instructions field to tell agents when to use the feedback tool:

If you encounter a limitation — a missing tool, incomplete data, wrong format, or any gap that prevents you from fully completing the user's request — call the feedback tool BEFORE responding to the user. Be specific about what you needed and what would have helped.

Without server instructions, agents may see the tool but not know when to call it. Adapt the text to your server's domain if needed.

How It Works

• Retries up to 2 times with exponential backoff (500ms, 1000ms)
• Retries on 429 (rate limit) and 5xx (server error) status codes
• Uses a static reqwest::Client for connection pooling and TLS session reuse
• On failure, logs the full payload with PATCHWORKMCP_UNSENT_FEEDBACK prefix for later replay
• Never panics — always returns a user-facing message

License

MIT