Crate brontes 

brontes: transform clap CLIs into MCP servers.

brontes walks a clap::Command tree, exposes every reachable command as an MCP tool, and ships a complete MCP server runtime over stdio so the resulting agent surface plugs straight into Claude Desktop, Cursor, and VSCode.

Two-line quick start

use clap::Command;

#[tokio::main]
async fn main() -> brontes::Result<()> {
    let cli = Command::new("my-cli")
        .version("0.1.0")
        .subcommand(Command::new("greet").about("Say hi"))
        .subcommand(brontes::command(None));            // [1] mount

    let matches = cli.clone().get_matches();
    match matches.subcommand() {
        Some(("mcp", sub)) => brontes::handle(sub, &cli, None).await,  // [2] dispatch
        Some(("greet", _)) => { println!("hi"); Ok(()) }
        _ => Ok(()),
    }
}

For tiny CLIs whose only purpose is the MCP server, collapse the ceremony into one line with run:

use clap::Command;

#[tokio::main]
async fn main() -> brontes::Result<()> {
    brontes::run(Command::new("my-cli").version("0.1.0"), None).await
}

Capabilities

• generate_tools — walk a clap::Command tree into a Vec<rmcp::model::Tool> for offline inspection, editor-config generation, or hand-rolled server wiring.
• command, handle, run — mount the mcp subtree and serve the generated tool list over stdio (mcp start) or streamable HTTP (mcp stream --host <addr> --port <num>).
• Config — selectors, annotations, per-flag schema overrides, default environment variables, server identity overrides, per-command description mode and full-text override.
• Selector, Middleware — first-match-wins routing rules and an async middleware boundary for wrapping tool execution.

Bug reports and feature requests: https://github.com/tj-smith47/brontes/issues.

Modules

selectors

Built-in factory functions for CmdMatcher and FlagMatcher.

Structs

Config

User-facing configuration for the mcp subtree.

MiddlewareCtx

Per-call context handed to Middleware.

Selector

Filtering rules that decide which commands become MCP tools and which flags those tools expose.

ToolAnnotations

Annotation hints attached to an MCP tool.

ToolInput

Request payload for a tool invocation.

ToolOutput

Response payload from a tool invocation.

Enums

DescriptionMode

Which clap field provides the primary text for an MCP tool description.

Error

Errors produced by brontes.

SchemaType

Coarse JSON Schema type for a clap flag.

Functions

command

Build the mcp subcommand subtree, ready to mount on a parent CLI.

generate_tools

Walk root, apply safety filters, apply first-match-wins selectors, and produce the MCP tool list ready to register with a server.

handle

Dispatch an mcp subcommand match.

run

One-call sugar: mount the mcp subtree, parse argv, dispatch.

Type Aliases

BoxedNext

One-shot async callable that runs the wrapped exec step.

CmdMatcher

Match a command by its space-joined path (e.g., "my-cli sub leaf").

FlagMatcher

Match a flag by inspecting its clap::Arg descriptor.

Middleware

Wrap tool-call execution with custom async logic.

MiddlewareResult

What a middleware (and the underlying exec step) ultimately produces.

Result

Result alias for fallible brontes operations.