semahash — Claude Code MCP server: what it does, how to install
This MCP server gives agents shared, hash-based references for semantic patterns. Use it when several agents need to check the same meaning.
claude mcp add semahash -- uvx semahashWhat semahash does
semahash treats semantic patterns as content-addressed references. An agent can search the vocabulary, resolve a name to its canonical reference, and run a handshake against that reference. The supplied description covers 617 cognitive patterns.
The MCP service exposes tools such as sema_search, sema_lookup, and sema_handshake. It can connect to Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, or Gemini CLI through uvx. A matching full reference identifies the resolved hashed content; it does not establish correctness or semantic equivalence.
The setup commands depend on uvx being available as the launcher. The server uses standard MCP stdio, while the CLI can work with a private pattern database instead of the bundled vocabulary.
What it helps with
- coordinate terms across several agents
- search a vocabulary by semantic topic
- check a canonical reference before use
- run a handshake at an agent boundary
- use a private pattern registry
Example prompts for the agent
- Search semahash for coordination patterns and run a handshake on
StateLock. - Resolve
StateLock, then verify its canonical reference before relying on it. - Find a pattern about locking and show its complete definition.
How to install semahash
Platform CLI
claude mcp add semahash -- uvx semahashuvx runs the command named after the package; if the README names another one, use uvx --from semahash <command>
Platform CLI
codex mcp add semahash -- uvx semahashuvx runs the command named after the package; if the README names another one, use uvx --from semahash <command>
Config file
{
"mcpServers": {
"semahash": {
"command": "uvx",
"args": [
"semahash"
]
}
}
}uvx runs the command named after the package; if the README names another one, use uvx --from semahash <command>
Config file
{
"servers": {
"semahash": {
"type": "stdio",
"command": "uvx",
"args": [
"semahash"
]
}
}
}uvx runs the command named after the package; if the README names another one, use uvx --from semahash <command>
Platform CLI
gemini mcp add semahash uvx semahashuvx runs the command named after the package; if the README names another one, use uvx --from semahash <command>
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about semahash
How do I install semahash in Claude Code?
Run claude mcp add semahash -- uvx semahash. Claude Code can then start the MCP server.
What does semahash do?
It searches and resolves semantic patterns, provides verifiable content references, and runs handshakes between agents.
What does a matching semahash reference prove?
A complete match identifies the resolved hashed content. It does not prove that the content is correct or semantically equivalent.
