Optimizing compiler for agent tools: many MCP servers or REST APIs in, one lean endpoint out.
The optimizing compiler for agent tool surfaces. Point it at your MCP servers, or just a REST API's OpenAPI spec, or even a docs page, and get back one endpoint that serves a smaller, smarter tool surface: cheaper for every agent that connects, more accurate on every task, with every call logged.
Connecting N MCP servers dumps every tool definition into the model's context, degrades tool selection, and forces improvised multi-hop call chains. toolc compiles the federation instead:
search_x/find_x/get_x)
merge into single facade tools with deterministic routingsearch_tools/call_tool) when you want maximum context savings131 tools across 5 live servers, 30 tasks × 3 trials, judged answers (full grid · consolidation run):
| condition | success | cost / completed task | tool-def context |
|---|---|---|---|
| raw (all 131 tools) | 96.7% | $0.2631 | ~24,360 tok |
| compiled + consolidate | 96.7% | $0.0411 (6.4× cheaper) | ~845 tok |
| consolidate, no selection | 100.0% | $0.1335 | ~14,506 tok |
Consolidation dominates both ends of the frontier: the selection surface is the cost lever, consolidation lifts accuracy everywhere. Every pass is a config toggle; pick the tradeoff per deployment.
git clone https://github.com/toolc-dev/toolc && cd toolc
pnpm install && pnpm -r test
# describe your federation
cp toolc.config.example.jsonc toolc.config.jsonc
# introspect it
node packages/cli/bin/toolc.mjs -c toolc.config.jsonc inspect
# compile (set ANTHROPIC_API_KEY for the rewrite/consolidate passes)
node packages/cli/bin/toolc.mjs -c toolc.config.jsonc compile
# serve the compiled surface over stdio (add to Claude as an MCP server)
node packages/cli/bin/toolc.mjs -c toolc.config.jsonc serve --mode compiled
A downstream can be an MCP server or a bare REST API:
{
"downstream": [
{ "id": "gh", "transport": { "type": "http", "url": "https://api.githubcopilot.com/mcp/" } },
{ "id": "nws", "transport": { "type": "openapi", "spec": "https://api.weather.gov/openapi.json" } }
]
}
See SELF_HOSTING.md for Docker deployment.
toolc.dev runs this same engine as a managed service: compiled HTTPS endpoints, a console with a playground and full-payload log explorer, docs-to-spec drafting, and error-driven fix recommendations.
packages/core: IR (Capability Graph), frontends (MCP, OpenAPI, docs synthesis), passes, emitpackages/gateway: runtime MCP server (mirror + compiled) with call logging and compactionpackages/cli: the toolc commandpackages/harness: benchmark runner, grading, reportspackages/shared: config schema, errorsThe engine (everything in this repository) is Apache-2.0, forever: anyone can compile and serve their own tool surfaces locally with the exact same compilation quality as the hosted product.
Source-derived launch command. Check the maintainer’s required arguments and credentials before running:
npx -y @toolc/cliMerge this template into ~/Library/Application Support/Claude/claude_desktop_config.json. Keep existing servers. Add any arguments, credentials, and permissions required by the maintainer; this template has not been install-tested.
{
"mcpServers": {
"dev-toolc-toolc": {
"command": "npx",
"args": [
"-y",
"@toolc/cli"
]
}
}
}Restart Claude Desktop completely for changes to take effect. Confirm the server appears connected in the client’s tool list, then try a read-only example from its documentation.
Claude Desktop setup reference@toolc/clinpmdev.toolc/toolc works with any MCP-compatible client. Copy the config snippet from the Configuration section above and add it to the file shown for your client, then restart the application.
~/Library/Application Support/Claude/claude_desktop_config.jsonRestart Claude Desktop completely for changes to take effect.~/.cursor/mcp.jsonRestart Cursor for changes to take effect..vscode/mcp.jsonReload VS Code window for changes to take effect.~/.codeium/windsurf/mcp_config.jsonRestart Windsurf for changes to take effect..mcp.jsonSave at the project root, then start Claude Code in that project and review the MCP server approval prompt. Keep real credentials out of shared files.