stx_call_contract · Bitcoin wallet MCP server MCP

WHAT IT DOES

What stx_call_contract does on Bitcoin wallet MCP server

AI agents invoke stx_call_contract to trigger actions in Bitcoin wallet MCP server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why stx_call_contract needs a policy

Executing a smart contract function on-chain triggers external operations with real blockchain effects. While some contract calls are read-only, 'public' Clarity functions can transfer tokens, modify state, or invoke other contracts irreversibly.

From the tool's definition Call a public Clarity smart contract function

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stx_call_contract Rate-limited

stx_call_contract stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "stx_call_contract": {
      "limits": [
        {
          "counter": "stx_call_contract_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Bitcoin wallet MCP server, so you can run agents against it safely.

FAQ

Questions about stx_call_contract

What does the stx_call_contract tool do? +

Call a public Clarity smart contract function. It is categorised as a Execute tool in the Bitcoin wallet MCP server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stx_call_contract? +

Register the Bitcoin wallet MCP server MCP server in PolicyLayer and add a rule for stx_call_contract: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Bitcoin wallet MCP server. Nothing to install.

What risk level is stx_call_contract? +

stx_call_contract is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit stx_call_contract? +

Yes. Add a rate_limit block to the stx_call_contract rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block stx_call_contract completely? +

Set action: deny in the PolicyLayer policy for stx_call_contract. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides stx_call_contract? +

stx_call_contract is provided by the Bitcoin wallet MCP server MCP server (markmhendrickson/mcp-server-bitcoin). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.