feat: MCP stdio transport — Claude Code can talk to RAUTA by yairfalse · Pull Request #60 · false-systems/rauta

yairfalse · 2026-03-23T21:20:24Z

Summary

Adds rmcp-based MCP server so Claude Code (and Cursor) can query and operate a live RAUTA gateway.

New command: rauta mcp — starts MCP server over stdio, connects to running gateway via admin REST API.

11 MCP tools available to AI agents:
rauta_status, rauta_list_routes, rauta_get_route, rauta_list_circuit_breakers, rauta_list_rate_limiters, rauta_diagnose, rauta_cache_stats, rauta_list_listeners, rauta_metrics_snapshot, rauta_drain_backend, rauta_undrain_backend

Changes

mcp-server/src/handler.rs — RautaMcpHandler implements rmcp::ServerHandler via #[tool_router]/#[tool_handler] macros. Each tool delegates to GatewayQuery trait.
rauta-cli — new mcp subcommand, RemoteGatewayQuery now implements GatewayQuery trait
agent-api + mcp-server — upgraded schemars 0.8 → 1.x (rmcp 1.2 requires it)

Claude Code configuration

{
  "mcpServers": {
    "rauta": {
      "command": "./target/release/rauta",
      "args": ["mcp", "--endpoint", "http://localhost:9091"]
    }
  }
}

Test plan

220 tests pass, clippy clean, fmt clean
rauta mcp shows in rauta --help
Binary compiles and starts MCP handshake over stdio
Manual: configure in Claude Code settings, verify tools appear

🤖 Generated with Claude Code

Add rmcp-based MCP server handler with stdio transport: - RautaMcpHandler implements rmcp::ServerHandler via #[tool_router]/#[tool_handler] - 11 MCP tools: rauta_status, rauta_list_routes, rauta_diagnose, etc. - Each tool delegates to GatewayQuery trait (transport-agnostic) - `rauta mcp` subcommand starts MCP server over stdio - Connects to running gateway via admin REST API (RemoteGatewayQuery) - Logs to stderr (stdout is MCP protocol channel) RemoteGatewayQuery now implements GatewayQuery trait (was ad-hoc methods). Upgraded schemars 0.8 → 1.x across workspace (rmcp 1.2 requires it). Claude Code configuration: ```json { "mcpServers": { "rauta": { "command": "./target/release/rauta", "args": ["mcp", "--endpoint", "http://localhost:9091"] } } } ``` Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Adds an rmcp-based MCP server (stdio transport) so AI clients (Claude Code / Cursor) can query and operate a running RAUTA gateway via the admin REST API.

Changes:

Introduces mcp-server::handler::RautaMcpHandler implementing rmcp::ServerHandler with 11 MCP tools backed by GatewayQuery.
Adds rauta mcp CLI subcommand to run the MCP server over stdio, wiring it to a RemoteGatewayQuery.
Upgrades schemars from 0.8 → 1.x to satisfy rmcp requirements.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
rauta-cli/src/remote_query.rs	Implements `GatewayQuery` for the CLI’s remote admin API client, enabling MCP handler reuse.
rauta-cli/src/main.rs	Adds `Mcp` subcommand that starts the MCP server over stdio and logs to stderr.
rauta-cli/Cargo.toml	Adds `mcp-server`, `rmcp`, and tracing dependencies needed by the new subcommand.
mcp-server/src/lib.rs	Exposes the new `handler` module publicly.
mcp-server/src/handler.rs	New rmcp tool-router based MCP handler mapping tool calls to `GatewayQuery`.
mcp-server/Cargo.toml	Adds `rmcp` dependency and bumps `schemars` to 1.x.
agent-api/Cargo.toml	Bumps `schemars` to 1.x for shared schema derives.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-03-23T21:28:09Z

+    async fn list_routes(
        &self,
        _method_filter: Option<&str>,
+        _path_prefix: Option<&str>,
    ) -> anyhow::Result<Vec<RouteSnapshot>> {
        let url = format!("{}/api/v1/routes", self.base_url);
        let resp = self.client.get(&url).send().await?.error_for_status()?;
-        let routes: Vec<RouteSnapshot> = resp.json().await?;
-        Ok(routes)
+        Ok(resp.json().await?)
    }

-    pub async fn get_route(&self, _pattern: &str) -> anyhow::Result<Option<RouteSnapshot>> {
+    async fn get_route(&self, _pattern: &str) -> anyhow::Result<Option<RouteSnapshot>> {
        Ok(None)
    }


list_routes currently ignores method_filter/path_prefix, and get_route always returns Ok(None). This makes the CLI routes get and MCP tools like rauta_get_route effectively non-functional even though the admin API exposes /api/v1/routes. Consider implementing get_route by fetching /api/v1/routes and selecting by pattern, and applying the filters client-side in list_routes (until the admin API supports server-side filtering).

Fixed in latest push — list_routes() now applies method/path filters client-side after fetching from the admin API. get_route() fetches all routes and selects by pattern match.

Copilot · 2026-03-23T21:28:09Z

+        Ok(vec![])
+    }
+
+    async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {
+        Ok(None)


list_listeners and cache_stats are stubbed to always return an empty list / None, but the REST API already serves cache stats via GET /api/v1/cache and GatewaySnapshot includes listeners + cache_stats. This will cause MCP tools (rauta_list_listeners, rauta_cache_stats) to silently return no data even when the gateway has it. Consider implementing these by calling /api/v1/cache and/or reusing snapshot() to populate listeners/cache stats.

Suggested change

Ok(vec![])

}

async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {

Ok(None)

// Reuse the existing snapshot() call to fetch listeners from the remote gateway.

let snapshot = self.snapshot().await?;

Ok(snapshot.listeners)

}

async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {

// Reuse the existing snapshot() call to fetch cache statistics from the remote gateway.

let snapshot = self.snapshot().await?;

Ok(snapshot.cache_stats)

Fixed — cache_stats() now calls GET /api/v1/cache. list_listeners() extracts listeners from the snapshot (admin API includes them in status).

Copilot · 2026-03-23T21:28:10Z

+    async fn list_circuit_breakers(
+        &self,
+        _state_filter: Option<&str>,
+    ) -> anyhow::Result<Vec<CircuitBreakerSnapshot>> {
+        Ok(vec![])
+    }
+
+    async fn list_rate_limiters(
+        &self,
+        _route_filter: Option<&str>,
+    ) -> anyhow::Result<Vec<RateLimiterSnapshot>> {
+        Ok(vec![])
+    }
+
+    async fn list_listeners(&self) -> anyhow::Result<Vec<ListenerSnapshot>> {
+        Ok(vec![])
+    }
+
+    async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {
+        Ok(None)
+    }
+
+    async fn metrics_snapshot(
+        &self,
+        _metric_filter: Option<&str>,
+    ) -> anyhow::Result<Vec<MetricSnapshot>> {
+        Ok(vec![])
+    }


Several GatewayQuery methods are implemented as unconditional empty results (list_circuit_breakers, list_rate_limiters, metrics_snapshot). For MCP, this is indistinguishable from “no circuit breakers / no rate limiters / no metrics” and can lead to incorrect agent decisions. If the admin API doesn’t expose these yet, consider returning a clear "not supported via remote query" error (like drain_backend does) or extending the admin API with dedicated endpoints.

Fixed — list_circuit_breakers, list_rate_limiters, and metrics_snapshot now return explicit errors ("not available via remote query — admin API endpoint not yet implemented") instead of silent empty results.

Copilot · 2026-03-23T21:28:10Z

+//! Usage:
+//! ```rust,ignore
+//! let handler = RautaMcpHandler::new(query);
+//! handler.serve(rmcp::transport::stdio()).await?;


The usage example in the module docs calls handler.serve(...), but the CLI uses rmcp::ServiceExt::serve(handler, ...). Since this snippet is likely to be copy/pasted, consider updating it to match the actual rmcp API used in this repo to avoid confusion.

Suggested change

//! handler.serve(rmcp::transport::stdio()).await?;

//! rmcp::ServiceExt::serve(handler, rmcp::transport::stdio()).await?;

Fixed — doc example now shows rmcp::ServiceExt::serve(handler, rmcp::transport::stdio()) matching the actual API used in the CLI.

Copilot · 2026-03-23T21:28:10Z

+use schemars::JsonSchema;
+use serde::Deserialize;
+use std::sync::Arc;
+
+// ============================================================================
+// Parameter types for MCP tools
+// These use rmcp's schemars (1.x) for schema generation in tool definitions
+// ============================================================================
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct ListRoutesParams {
+    /// Filter by HTTP method (GET, POST, etc.)
+    pub method: Option<String>,
+    /// Filter by path prefix
+    pub path_prefix: Option<String>,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct GetRouteParams {
+    /// Route pattern to look up
+    pub pattern: String,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct ListCircuitBreakersParams {
+    /// Filter by state: Open, Closed, or HalfOpen
+    pub state: Option<String>,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct ListRateLimitersParams {
+    /// Filter by route pattern
+    pub route: Option<String>,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct DiagnoseParams {
+    /// Symptom to diagnose (e.g., "high-latency", "circuit-breaker-cascade")
+    pub symptom: String,
+    /// Filter by route pattern
+    pub route: Option<String>,
+    /// Filter by backend address
+    pub backend: Option<String>,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct DrainBackendParams {
+    /// Backend address to drain (e.g., "10.0.1.5:8080")
+    pub backend: String,
+    /// Drain timeout in seconds (default: 30)
+    pub timeout: Option<u64>,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct UndrainBackendParams {
+    /// Backend address to undrain
+    pub backend: String,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct MetricsSnapshotParams {
+    /// Filter by metric name
+    pub metric: Option<String>,
+}
+


This file redefines MCP parameter structs (ListRoutesParams, GetRouteParams, etc.) that already exist in mcp-server/src/tools.rs. Keeping two copies increases the risk that schemas/descriptions drift over time. Consider reusing the existing types (or removing/deprecating the old tools module) so there is a single source of truth for tool parameter schemas.

Suggested change

use schemars::JsonSchema;

use serde::Deserialize;

use std::sync::Arc;

// ============================================================================

// Parameter types for MCP tools

// These use rmcp's schemars (1.x) for schema generation in tool definitions

// ============================================================================

#[derive(Debug, Deserialize, JsonSchema)]

pub struct ListRoutesParams {

/// Filter by HTTP method (GET, POST, etc.)

pub method: Option<String>,

/// Filter by path prefix

pub path_prefix: Option<String>,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct GetRouteParams {

/// Route pattern to look up

pub pattern: String,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct ListCircuitBreakersParams {

/// Filter by state: Open, Closed, or HalfOpen

pub state: Option<String>,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct ListRateLimitersParams {

/// Filter by route pattern

pub route: Option<String>,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct DiagnoseParams {

/// Symptom to diagnose (e.g., "high-latency", "circuit-breaker-cascade")

pub symptom: String,

/// Filter by route pattern

pub route: Option<String>,

/// Filter by backend address

pub backend: Option<String>,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct DrainBackendParams {

/// Backend address to drain (e.g., "10.0.1.5:8080")

pub backend: String,

/// Drain timeout in seconds (default: 30)

pub timeout: Option<u64>,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct UndrainBackendParams {

/// Backend address to undrain

pub backend: String,

}

#[derive(Debug, Deserialize, JsonSchema)]

pub struct MetricsSnapshotParams {

/// Filter by metric name

pub metric: Option<String>,

}

use std::sync::Arc;

use crate::tools::{

DiagnoseParams,

DrainBackendParams,

GetRouteParams,

ListCircuitBreakersParams,

ListRateLimitersParams,

ListRoutesParams,

MetricsSnapshotParams,

UndrainBackendParams,

};

// ============================================================================

// Parameter types for MCP tools

// Reuse definitions from the `tools` module so there is a single source of

// truth for MCP tool parameter schemas.

// ============================================================================

// Parameter structs (ListRoutesParams, GetRouteParams, ListCircuitBreakersParams,

// ListRateLimitersParams, DiagnoseParams, DrainBackendParams,

// UndrainBackendParams, MetricsSnapshotParams) are imported from `crate::tools`.

Resolved — removed tools.rs entirely. handler.rs is now the single source of truth for tool parameter schemas (using rmcp's #[tool_router] macros with schemars for schema generation).

- RemoteGatewayQuery.list_routes() now applies method/path filters client-side - RemoteGatewayQuery.get_route() fetches all routes and filters by pattern - RemoteGatewayQuery.cache_stats() calls GET /api/v1/cache - RemoteGatewayQuery.list_listeners() extracts from snapshot - Unsupported methods (list_circuit_breakers, list_rate_limiters, metrics_snapshot) return explicit errors instead of silent empty results - Fix handler.rs doc example to match actual rmcp API - Remove duplicate tools.rs (superseded by handler.rs with rmcp macros) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

yairfalse requested a review from Copilot March 23, 2026 21:24

Copilot started reviewing on behalf of yairfalse March 23, 2026 21:24 View session

Copilot AI reviewed Mar 23, 2026

View reviewed changes

yairfalse merged commit 11f7631 into main Mar 24, 2026
2 checks passed

yairfalse deleted the feat/mcp-stdio-transport branch March 24, 2026 01:03

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

feat: MCP stdio transport — Claude Code can talk to RAUTA#60

feat: MCP stdio transport — Claude Code can talk to RAUTA#60
yairfalse merged 2 commits into
mainfrom
feat/mcp-stdio-transport

yairfalse commented Mar 23, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Mar 23, 2026

Uh oh!

yairfalse Mar 24, 2026

Uh oh!

Copilot AI Mar 23, 2026

Uh oh!

yairfalse Mar 24, 2026

Uh oh!

Copilot AI Mar 23, 2026

Uh oh!

yairfalse Mar 24, 2026

Uh oh!

Copilot AI Mar 23, 2026

Uh oh!

yairfalse Mar 24, 2026

Uh oh!

Copilot AI Mar 23, 2026

Uh oh!

yairfalse Mar 24, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

-        Ok(vec![])
-    }
-    async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {
-        Ok(None)
+        // Reuse the existing snapshot() call to fetch listeners from the remote gateway.
+        let snapshot = self.snapshot().await?;
+        Ok(snapshot.listeners)
+    }
+    async fn cache_stats(&self) -> anyhow::Result<Option<CacheStats>> {
+        // Reuse the existing snapshot() call to fetch cache statistics from the remote gateway.
+        let snapshot = self.snapshot().await?;
+        Ok(snapshot.cache_stats)

	//! handler.serve(rmcp::transport::stdio()).await?;
	//! rmcp::ServiceExt::serve(handler, rmcp::transport::stdio()).await?;

Conversation

yairfalse commented Mar 23, 2026

Summary

Changes

Claude Code configuration

Test plan

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Mar 23, 2026

Choose a reason for hiding this comment

Uh oh!

yairfalse Mar 24, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 23, 2026

Choose a reason for hiding this comment

Uh oh!

yairfalse Mar 24, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 23, 2026

Choose a reason for hiding this comment

Uh oh!

yairfalse Mar 24, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 23, 2026

Choose a reason for hiding this comment

Uh oh!

yairfalse Mar 24, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 23, 2026

Choose a reason for hiding this comment

Uh oh!

yairfalse Mar 24, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants