MCP Server Reference

The Crux MCP server is a single 6.6MB Rust binary (crux mcp start) exposing 66 tools via the Model Context Protocol. Any MCP-compatible AI assistant connects with one config line.

Connection

{
  "type": "stdio",
  "command": "/path/to/crux",
  "args": ["mcp", "start"]
}

Session Tools

Tool Description
get_session_state Current mode, tool, working_on, decisions
update_session Update working_on, add decision, add file
restore_context Restore full session context — call at session start
write_handoff Write handoff for next session
read_handoff Read handoff from previous session
recover_session Recover context from corrupted Claude Code sessions

Knowledge & Memory

Tool Description
lookup_knowledge Search knowledge entries by keyword
promote_knowledge Promote project knowledge to user scope
remember_fact Remember a fact for future sessions
recall_memories Search stored memories
forget_fact Remove a stored memory
list_all_memories List all stored memories

Impact Analysis

Tool Description
analyze_impact Rank files by relevance (git + grep + AST)
search_code Search codebase for files and symbols
index_codebase Build/refresh the codebase index

Git Context

Tool Description
git_context File history, risk score
git_diff Current uncommitted changes
git_risky_files Files with highest churn
git_suggest_commit Suggest commit message from staged changes

Safety Pipeline

Tool Description
validate_script Gate 1: preflight validation
get_active_gates Active gates for a risk level
get_pipeline_config Current pipeline configuration
start_tdd_gate Gate 2: start TDD enforcement
check_tdd_status TDD gate status
start_security_audit Gate 3: start security audit
security_audit_summary Security audit results
audit_script_8b Gate 4: 8B adversarial audit (Ollama)
audit_script_32b Gate 5: 32B second opinion (Ollama)

Design Validation

Tool Description
start_design_validation WCAG/brand checks
design_validation_summary Validation results
check_contrast WCAG contrast ratio for two colors

Modes

Tool Description
get_mode_prompt Full prompt text for a mode
list_modes All available modes

Logging

Tool Description
log_correction Log a correction for learning
log_interaction Log a conversation message

Tool Switching

Tool Description
switch_tool_to Switch to another AI tool

MCP Server Registry

Tool Description
register_mcp_server Register an external MCP server
remove_mcp_server Remove a server
list_mcp_servers List registered servers

Build-in-Public

Tool Description
bip_generate Check triggers, gather content for a draft
bip_approve Approve and queue to Typefully
bip_status Current BIP state and counters
bip_get_analytics Engagement analytics

Model Routing

Tool Description
get_model_for_task Recommended model for a task type
get_available_tiers Available models at each tier (auto-discovers Ollama)
get_mode_model Recommended model for a mode
get_model_quality_stats Success rates per model per task

Figma Integration

Tool Description
figma_get_tokens Extract design tokens from Figma
figma_get_components Get component library

Cross-Project

Tool Description
register_project Register for cross-project analytics
get_cross_project_digest Digest spanning all projects

Background Processors

Tool Description
check_processor_thresholds Which thresholds are exceeded
run_background_processors Run due processors
get_processor_status When each processor last ran

Diagnostics

Tool Description
verify_health Health checks report
get_project_context Auto-generated PROJECT.md
get_digest Daily digest