AI client configuration

The server speaks MCP over stdio. The standard way to configure it is the npx form, which runs the published npm package. To run a locally built binary instead, replace npx -y cmsis-dap-mcp with your binary path — the server behaves identically.

Configuration styles

There are three ways to point an MCP client at a server:

Style	Example	When to use
`npx` package (standard)	`command = "npx", args = ["-y", "cmsis-dap-mcp"]`	Published releases; first launch downloads and caches the package
Local binary	`command = "/path/to/cmsis-dap-mcp"`	Unpublished or locally built servers, offline use, exact version pinning
Remote URL	`url = "https://..."`	Streamable-HTTP MCP servers (not supported by this project yet)

To pin a version with npx: npx -y cmsis-dap-mcp@0.5.0. If you are developing this repository, point the client at target/release/cmsis-dap-mcp so the freshly built binary is used without publishing.

Server command-line options

All options are optional — the server starts fine with no arguments and enters a to-be-configured state. Everything below (except logging) can also be changed at runtime via the update_config / reload_config / get_config MCP tools without a restart.

Option	Meaning
`--allow-destructive`	enable `erase_flash` / `program_flash` and destructive script commands at startup
`--tcp PORT`	also serve the remote JSON-RPC TCP server on `127.0.0.1:PORT`
`--gdb-port PORT`	also start a GDB server on `127.0.0.1:PORT`
`--config-file FILE`	JSON config file (`allow_destructive`, `tcp_port`, `gdb_port` keys); loaded at startup, watchable for changes
`--probe-id ID`	default probe id for connect
`--protocol swd\|jtag`	default debug protocol (default `swd`)
`--speed-khz N`	default SWD/JTAG clock speed
`--target NAME`	default target chip name
`--svd FILE`	SVD file to load at startup
`--target-yaml FILE`	target YAML to pre-load into the chip registry
`--log-level LEVEL`	tracing filter; logs go to stderr (default `info`)
`--log-file FILE`	write logs to a file instead of stderr

Startup-only (not changeable at runtime): --log-level, --log-file, the --config-file path itself (its contents can be reloaded), and the backend registry seed (--target-yaml; define_chip adds to it at runtime). A GDB server port cannot be changed once the server is running.

Precedence: CLI flags > config file > defaults; runtime update_config overrides both.

Codex

codex mcp add cmsis-dap -- npx -y cmsis-dap-mcp

Or add to ~/.codex/config.toml:

[mcp_servers.cmsis-dap]
command = "npx"
args = ["-y", "cmsis-dap-mcp"]

For a local build, use command = "/path/to/cmsis-dap-mcp". Verify with codex mcp list. The Codex desktop app loads the server when a new session starts.

Claude Code

claude mcp add --scope local cmsis-dap -- npx -y cmsis-dap-mcp

For a local build, replace npx -y cmsis-dap-mcp with the binary path. Verify with claude mcp list (shows √ Connected).

opencode

opencode mcp add cmsis-dap -- npx -y cmsis-dap-mcp

Or add to ~/.config/opencode/opencode.jsonc:

"cmsis-dap": {
  "type": "local",
  "command": ["npx", "-y", "cmsis-dap-mcp"],
  "enabled": true
}

For a local build, replace the command array with ["/path/to/cmsis-dap-mcp", "--log-level", "warn"]. Verify with opencode mcp list.

Other MCP clients

{
  "mcpServers": {
    "cmsis-dap": {
      "command": "npx",
      "args": ["-y", "cmsis-dap-mcp"]
    }
  }
}

End-to-end example (verified)

The same task below was executed successfully by Claude Code and opencode against a real CMSIS-DAP probe:

1. list_probes
2. connect {protocol: swd, speed_khz: 1000}
3. read_memory {address: 0x20000000, width: u32, count: 4}
4. halt
5. read_core_register {name: pc}
6. resume

Observed results:

probe id : 0123456789AB (CMSIS-DAP, vendor 0x0416)
memory   : [64000000, 1, 3, 0]
pc       : 134228884 (0x08002B94)

Notes:

When passing arguments from a model, use decimal integers or strings; some clients reject hex literals in JSON arguments (e.g. 0x20000000). Decimal 536870912 is equivalent.
Write tools such as connect, halt and resume may be governed by the client approval policy.
If the tools do not appear, restart the client after adding the server.

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