@deterministic-compute/mcp-server

Deterministic compute MCP stdio server for Codex and other MCP clients. It exposes exact arithmetic, expressions, unit conversion, finance calculators, result verification, and expected-value generation through the Rust compute-cli.

Codex Install

Install the server into Codex with one command:

codex mcp add deterministic-compute -- npx -y @deterministic-compute/mcp-server

Restart Codex, then run /mcp in the TUI or:

codex mcp list

Codex stores the server in ~/.codex/config.toml as a local stdio MCP server:

[mcp_servers.deterministic-compute]
command = "npx"
args = ["-y", "@deterministic-compute/mcp-server"]

Requirements

• Node.js >=20.
• Linux x64 for the current packaged native compute-cli binary.

Other platforms can still use the server by building compute-cli from this repository and pointing the MCP wrapper at it:

export DETERMINISTIC_COMPUTE_CLI_COMMAND="/absolute/path/to/compute-cli"
export DETERMINISTIC_COMPUTE_CLI_ARGS_JSON="[]"

Local Development

From the repository root:

npm ci --prefix apps/mcp-server-ts
npm --prefix apps/mcp-server-ts run build
node apps/mcp-server-ts/dist/index.js

When no packaged native binary is present, the server falls back to:

cargo run --quiet --manifest-path crates/compute-cli/Cargo.toml --

Real Codex Smoke Test

From the repository root, with Codex already authenticated:

scripts/codex-mcp-smoke.sh

This builds the local Rust CLI and TypeScript server, then runs codex exec with a transient deterministic-compute-local stdio MCP server. The smoke test asks Codex to call every registered MCP tool once, validates representative arithmetic, expression, unit conversion, finance, verification, and expected-value results, and does not persist any MCP configuration.

The transient command marks the deterministic compute tools as approved for the run so non-interactive codex exec can complete the tool calls.

To attach the local checkout persistently for manual Codex sessions:

codex mcp add deterministic-compute-local \
  --env DETERMINISTIC_COMPUTE_CLI_COMMAND="$PWD/target/debug/compute-cli" \
  --env DETERMINISTIC_COMPUTE_CLI_ARGS_JSON='[]' \
  -- node "$PWD/apps/mcp-server-ts/dist/index.js"

Release Packaging

The current test package stages the Linux x64 Rust CLI binary and builds the TypeScript server:

npm --prefix apps/mcp-server-ts run build:package
npm --prefix apps/mcp-server-ts pack --dry-run

For now, the package includes:

• compute-cli-linux-x64

Future general releases should add the remaining platform binaries before documenting broad npx support.