Semahash MCP server

by emergent-wisdom·io.github.emergent-wisdom/semahash·v0.10.0·14 stars

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Content-addressed semantics: fail-closed handshakes over 617 cognitive patterns.

A86/100grade A

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Safety scan

A86/100

full report

Adoption

Growing

14 stars445 downloads/wk

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If you have run it, two minutes of your experience saves the next person an afternoon.

Semahash tools (17, 1 write)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

sema_graph_skeleton
Ultra-minimal graph overview (~150 tokens). Shows regions, hubs, and recent activity.
sema_handshake
Byte-level definition agreement check between two agents.
sema_library_install
Install a published library by name, path, or library.json URL.
sema_library_login
Store a registry key that the user created on their profile page.
sema_library_publishwrite action
Publish a library release on the public registry.
sema_library_search
Find published Sema libraries on a registry, https://semahash.org by default.
sema_lookup
Lookup a pattern by its Sema reference (Handle#stub).
sema_propose_context
Propose a shared definition set for multi-agent coordination.
sema_reset_session
Reset the session pattern cache.
sema_resolve
Get a pattern with its dependencies expanded.
sema_root
Get both aggregate roots of the active vocabulary.
sema_search
Search Sema patterns by name, description, or meaning (semantic search).
sema_stats
Get statistics about the Sema vocabulary.
sema_tree
Browse the vocabulary structure organized by layer and category.
sema_use
Switch the active vocabulary database without restarting.
sema_validate
Validate a pattern JSON using the same rules as the mint pipeline.
sema_verify_context
Verify a semantic context proposed by another agent.

Public scan report

scanner v0.1.10 · 2026-10-16 · same rubric, same numbers if you re-run it

1 medium

Code scan678 source files scanned20/25
–Live reliabilityno gateway calls yet and no remote to proben/a
–Tool poisoningtools not inspected (local package is not executed); not countedn/a
Auth qualitylocal package, no credentials required12/15
Maintenancelast push 5 days ago15/15
Maintainer identityregistry namespace matches repository owner; GitHub account older than a year9/10

Findings (1)

mediumeval / new Function usedexec.eval

semahash-0.10.0/src/sema/server/static/assets/GraphPage-ChR36yZe.js: …n;function e(s,o){let a=t(s,o),{Body:l}=new Function(a)();return l}function t(s,o){return` ${…

Overall 86/100. Components that don't apply are left out of the denominator. Any critical finding is an F.Rubric Appeal a finding JSON

How Semahash compares

Against every graded MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score: 86/100; higher than 72% of 48,255 servers
Tools: 17; the typical server has 7
Tools that change things: 6%; typical: 0%. Fewer write tools means less an agent can break
GitHub stars: 14; more than 90% of 28,688 servers
Downloads a week: 445; more than 86% of 12,191 servers with a package

What its tools let an agent do: 16 read · 1 change

Release history: 5 versions in the registry since 2026-09-06, latest 2026-10-11, typically one every 11 days.

Install Semahash in Claude Code, Cursor or VS Code

claude mcp add semahash -- uvx semahash

Add to Cursor

What the publisher says

From the Semahash repository's README, as published. We do not edit it. Read it on GitHub

Sema: When the Hash Is the Word

Content-addressed semantics for multi-agent coordination.

Sema is a content-addressed reference system for reasoning and communication. Participants encode and hash information under an agreed representation, then reuse the content address as a verifiable reference, optionally paired with a human-readable handle. Matching full references establishes identity of the resolved hashed content; semantic equivalence, correctness, and enforcement remain separate questions.

Web: semahash.org · Discord: Join

Install

MCP Server (recommended)

Add to any MCP client (Claude Code, Cursor, VS Code, Windsurf, Claude Desktop):

{
  "mcpServers": {
    "sema": {
      "command": "uvx",
      "args": ["--from", "semahash[mcp]", "sema", "mcp"]
    }
  }
}

Or via Claude Code CLI:

claude mcp add sema -- uvx --from "semahash[mcp]" sema mcp

This uses uv to download, install, and run sema in an isolated environment on first invocation, then caches it for subsequent calls.

Claude Code plugin (MCP server + skill)

Sema also ships as a Claude Code plugin — MCP server plus a skill that teaches the agent the search/resolve/mint/handshake workflow:

# One-time: add the Emergent Wisdom marketplace
claude plugin marketplace add emergent-wisdom/marketplace

# Install the plugin
claude plugin install sema

This gives you the MCP server and the sema-usage skill (auto-loaded), which teaches when to search vs mint, how to embed handles in text, and how to verify meaning at boundaries. The skill is a Claude Code convenience — the MCP server works with any client.

For local development:

claude --plugin-dir /path/to/sema

Permanent install (pip)

pip install "semahash[mcp]"

For CLI-only use (no MCP server):

pip install semahash

Quick Start

Use with AI Agents (MCP)

Already covered above via the JSON config or pip install path. For development against this repo:

git clone https://github.com/emergent-wisdom/sema.git
pip install -e "./sema[mcp]"

Your agent now has access to semasearch, semalookup, sema_handshake, and 9 more tools. Any MCP-compatible client works — Sema exposes a standard stdio server.

Verify it works — ask your agent: "Search sema for coordination patterns and handshake on StateLock"

Sema exposes a standard MCP stdio server — any MCP-compatible client works, including OpenClaw (openclaw mcp set sema '{"command":"uvx","args":["--from","semahash[mcp]","sema","mcp"]}').

Use via CLI

# Search the vocabulary
sema search "coordination"

# Look up a specific pattern
sema resolve StateLock

# Print a pattern's full definition
sema show StateLock

# Browse the graph structure
sema skeleton

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Grade history

2026-10-16restoreB → Ascore 86: eval / new Function used

Semahash: common questions

Is Semahash MCP server safe?: Yes, by our scan: it is graded A (86/100). Read the Semahash safety report
How do I install Semahash?: It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Semahash need an API key?: Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is Semahash maintained?: The last commit was 24 days ago (2026-10-11). The latest release is v0.10.0.
How does Semahash compare with other MCP servers?: safety score 86/100 (higher than 72% of 48,255 servers); tools 17 (the typical server has 7); tools that change things 6% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.