Module dev_mcp 

Available on non-WebAssembly only.

app.dev_mcp(): an MCP endpoint for a coding agent (18.28.0). app.dev_mcp(): an MCP endpoint that lets a coding agent look inside the application it is working on — its routes and the middleware around them, its effective configuration (secrets hidden), its layout and rws.app.toml (crate::app_manifest), the last requests and errors, and with a model-* feature its models, database schema and migrations. Since 18.28.0 (roadmap #85, #87).

Off unless the process runs with RWS_ENV=dev (RwsEnv) or a bearer token is configured (MCP_TOKEN by default, DevTools::token): in production without a token DevMcpExt::dev_mcp mounts nothing and the app is served as it is. With a token every request to the endpoint must carry Authorization: Bearer <token> (McpServer::require_bearer); in development without one the endpoint is open, so keep the port local or set a token.

use rust_web_server::app::App;
use rust_web_server::core::New;
use rust_web_server::dev_mcp::DevMcpExt;
use rust_web_server::response::Response;

let app = App::with_state(())
    .get("/hello", |_, _, _, _| Response::new())
    .dev_mcp(); // RWS_ENV=dev: /mcp lists GET /hello

DevTools chooses what is mounted: the operations tools of the rws binary too (DevTools::with_ops, also usable alone as ops_tools), a database, a migrations directory, read-only mode.

Structs

DevTools

What DevMcpExt::dev_mcp_with mounts, and when.

Enums

DevMcp

An app with the dev MCP endpoint in front of it (DevMcp::On), or the app alone (DevMcp::Off) — what DevMcpExt::dev_mcp returns. An Application either way.

RwsEnv

The environment kind named by RWS_ENV.

Constants

DEFAULT_TOKEN_ENV

The environment variable a token is read from unless DevTools::token or DevTools::token_env says otherwise — the one the rws binary’s /mcp uses.

DEV_WRITE_TOOLS

The tools that change something, besides OPS_WRITE_TOOLS: the migration runners (with a model-* feature and a migrations directory).

OPS_WRITE_TOOLS

The operations tools that change the running server. They are what crate::admin::access::McpAuditLayer records, and what super::DevTools::read_only leaves out.

Traits

DevMcpExt

.dev_mcp() on every Application — AppWithState, App, WithMiddleware, AsyncAppWithState and the rest.

Functions

masked

value as config shows it: crate::entry_point::shown (secrets by name, PKCS#11 PINs), and a password in a URL’s user info (postgres://app:pw@db/app) hidden too.

ops_tools

Register the 25 operations tools on mcp — the rws binary’s set: configuration, metrics, routes (routes as (method, pattern)), the response cache (cache’s stats and purge; both tools are left out without one), rate limits, CORS, static files, config reload, maintenance mode, the IP blocklist, runtime feature flags, the request log, authorization tuples and checks, and the traffic summary. Each carries ToolAnnotations: read-only, or changing (destructive except unblock_ip).