io.github.heuristicolab/ctxfw
context-firewall-mcp
Is the io.github.heuristicolab/ctxfw MCP server down? No. It answered initialize and tools/list in the probe of 2026-10-26.
Zero-egress AI Agent Firewall: SARA prompt injection defense, AST context pruning & MCP governance.
alive probed 2026-11-14 · unchanged since 2026-10-26
- Run it
- uvx ctxfw@4.1.1 (stdio, probed in a container with the network off)
- Host
- pypi.org
- Reports itself as
- context-firewall-mcp 4.1.1
- Capabilities
- tools
- Instructions
- 744 characters
- Of a 1M window
- 0.2 % of a 1M context window
- Count
- 2.3k tokens in Claude Opus 5.5, exact, measured 2026-10-26. With the Claude Code prefix mcp__…__ on each tool name: 2.3k. The o200k_base estimate is 1.2k. Counted again when the tool definitions change. Method.
- Repository
- https://github.com/heuristicolab/ctxfw
- Registry
- active, updated 2026-10-25 · registry entry
Most expensive tools
The Claude column scales the o200k estimate of each tool by this server's ratio of exact to estimate, 1.83×.
| Tool | ≈ Claude tokens | o200k estimate | Share of this server |
|---|---|---|---|
| evaluate_patch | 782 | 427 | 35 % |
| query_audit_ledger | 440 | 240 | 20 % |
| prune_file | 423 | 231 | 19 % |
| resolve_context_bundle | 386 | 211 | 17 % |
| evaluate_spec_axioms | 220 | 120 | 10 % |
Compare this server with others.
More servers
Other registry entries on pypi.org, the ones next to this name; all of them.
- CSJN — Corte Suprema de Justicia de la Nación io.github.hernan-cc/csjn-mcp · needs mcp<2
- JUBA — Jurisprudencia de Buenos Aires io.github.hernan-cc/juba-mcp · needs mcp<2
- JusCABA — Justicia CABA io.github.hernan-cc/juscaba-mcp · needs mcp<2
- SAIJ — Jurisprudencia Argentina io.github.hernan-cc/saij-mcp · needs mcp<2
- Dante IX — Autonomous Brand & GEO Agency MCP io.github.heuristicolab/dante-mcp · alive
- US Macro io.github.hgus107/us-macro-mcp · needs mcp<2
- io.github.hhopke/intervals-icu-mcp · alive
- io.github.hidai25/evalview-mcp · crashed on start
Servers that mention governance or injection.
- ai.geodesiclabs/governance-platform · alive
- ai.kanonik/kanonik · needs auth
- Modulos AI Governance Platform ai.modulos/demo-booking · alive
- Nebelus Agent Construction ai.nebelus/construction · needs auth
- ai.plith/plith · alive
- ai.responsibleailabs/rail-score · no DNS
- Rithmo ai.rithmo/rithmo · needs auth
- ThinkNEO Control Plane ai.thinkneo/control-plane · no DNS
Badge for the README
The result of the latest probe, the tool count and the token cost. The feed has an entry for every probe that changed them.
A mail when this server changes
Stops answering, comes back, tool set or cost changes. One confirmation mail first, a stop link in every mail.
For the publisher
- The server answers initialize and tools/list. Nothing to fix.