@txfence/mcp

MCP (Model Context Protocol) server that exposes txfence capabilities to AI assistants. Integrates with Claude, Cursor, and any MCP-compatible tool.

MCP server configuration

Add to your MCP server config (e.g., .cursor/mcp.json or claude_desktop_config.json):

{
  "mcpServers": {
    "txfence": {
      "command": "npx",
      "args": ["txfence", "mcp"],
      "env": {
        "TXFENCE_CONFIG": "./txfence.config.ts"
      }
    }
  }
}

Tools

txfence_simulate

Runs the full txfence simulation pipeline without executing on-chain.

Input:

{
  "action": {
    "kind": "transfer",
    "chain": "ethereum",
    "token": { "token": "ETH", "amount": "100000000000000000", "decimals": 18 },
    "to": "0xRecipient"
  }
}

Output: SimulationResult with coverageLevel, gasEstimate, wouldRevert, caveats.

txfence_check_policy

Evaluates an action against the current policy without simulation or execution. Fast — no RPC calls.

Input: Same as txfence_simulate.

Output: PolicyEvaluation with passed, checksRun, rejectionReason if failed.

txfence_submit

Submits an action through the full txfence pipeline.

Input:

{
  "action": { ... },
  "dryRun": true
}

Output: PipelineResult with full status, evaluation, simulation, and receipt (if executed).

txfence_get_receipt

Retrieves a stored execution receipt by transaction hash.

Input: { "txHash": "0x..." }

Output: SuccessReceipt with action details, evaluation result, and on-chain confirmation.

txfence_explain_rejection

Returns a human-readable explanation of a policy rejection reason.

Input: { "rejectionReason": "spend_exceeds_cap" }

Output: Plain-text explanation with the specific check that failed and how to fix it.

txfence_diff_policies

Computes the diff between two policy objects and returns the blast radius of the change.

Input:

{
  "before": { "maxSpendPerTx": { "token": "USDC", "amount": "10000000000", "decimals": 6 } },
  "after": { "maxSpendPerTx": { "token": "USDC", "amount": "5000000000", "decimals": 6 } }
}

Output: A list of changed fields with the effect of each change (more restrictive / less restrictive) and any actions that would be affected.