Skip to content

feat(mcp): serve a usage spec to an agent over stdio #746

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
jdx merged 5 commits into from
Jul 27, 2026
Merged

feat(mcp): serve a usage spec to an agent over stdio #746

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
7241977
feat(mcp): serve a usage spec to an agent over stdio
jdx Jul 27, 2026
bf695e7
refactor(mcp): build on rmcp rather than hand-rolled JSON-RPC
jdx Jul 27, 2026
0ae48da
fix(mcp): report the global flags a command inherits
jdx Jul 27, 2026
58a2573
fix(mcp): resolve inherited flags through the parser, not by hand
jdx Jul 27, 2026
259021a
fix(mcp): make the two tools agree on how a command is named
jdx Jul 27, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
217 changes: 217 additions & 0 deletions Cargo.lock
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

3 changes: 3 additions & 0 deletions cli/Cargo.toml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -34,11 +34,14 @@ kdl = "6"
log = "0.4"
miette = { version = "7", features = ["fancy"] }
regex = "1"
rmcp = { version = "2", features = ["server", "transport-io", "macros", "schemars"] }
schemars = "1"
serde = { version = "1", features = ["derive"] }
serde_json = "1.0"
serde_with = "3"
tera = "2"
thiserror = "2"
tokio = { version = "1", features = ["rt", "macros", "io-std"] }
usage-lib = { workspace = true, features = ["clap", "docs", "unstable_choices_env"] }
xx = "2"

Expand Down
23 changes: 23 additions & 0 deletions cli/assets/fig.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -532,6 +532,29 @@ const completionSpec: Fig.Spec = {
template: "filepaths",
},
},
{
name: ["mcp", "mcp-server"],
description: "Serve a usage spec over the Model Context Protocol",
options: [
{
name: ["-f", "--file"],
description: 'Usage spec file (not "-": stdin is the MCP transport)',
isRepeatable: false,
args: {
name: "file",
template: "filepaths",
},
},
{
name: ["-s", "--spec"],
description: "Raw string spec input",
isRepeatable: false,
args: {
name: "spec",
},
},
],
},
{
name: "powershell",
description: "Execute a shell script using PowerShell",
Expand Down
22 changes: 22 additions & 0 deletions cli/assets/usage.1
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,12 @@ Generate a type\-safe SDK from a usage spec
\fBlint\fR
Lint a usage spec file for common issues
.TP
\fBmcp\fR
Serve a usage spec over the Model Context Protocol
.RS
\fIAliases: \fRmcp\-server
.RE
.TP
\fBpowershell\fR
Execute a shell script with the specified shell
.TP
Expand Down Expand Up @@ -359,6 +365,22 @@ Treat warnings as errors
.TP
\fB<FILE>\fR
A usage spec file to lint, use "\-" to read from stdin
.SH "USAGE MCP"
Serve a usage spec over the Model Context Protocol

Reads JSON\-RPC over stdin and writes responses to stdout, which is how MCP
clients launch a local server. Point one at `usage mcp \-f mycli.usage.kdl`.
.PP
\fBUsage:\fR usage mcp [OPTIONS]
.PP
\fBOptions:\fR
.PP
.TP
\fB\-f, \-\-file\fR \fI<FILE>\fR
Usage spec file (not "\-": stdin is the MCP transport)
.TP
\fB\-s, \-\-spec\fR \fI<SPEC>\fR
Raw string spec input
.SH "USAGE POWERSHELL"
Execute a shell script with the specified shell

Expand Down
Loading
Loading