Sign a message using a COTI private key. This creates a cryptographic signature that proves the message was signed by the owner of the private key. The AI assistant should pass the private key from context. Returns the signature.
Handles credentials or secrets (private_key)
Part of the COTI MCP Server MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents call sign_message to retrieve information from COTI MCP Server without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though sign_message only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
tools:
sign_message:
rules:
- action: allowSee the full COTI MCP Server policy for all 44 tools.
Sign a message using a COTI private key. This creates a cryptographic signature that proves the message was signed by the owner of the private key. The AI assistant should pass the private key from context. Returns the signature.. It is categorised as a Read tool in the COTI MCP Server MCP Server, which means it retrieves data without modifying state.
Add a rule in your Intercept YAML policy under the tools section for sign_message. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the COTI MCP Server MCP server.
sign_message is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the sign_message rule in your Intercept 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.
Set action: deny in the Intercept policy for sign_message. 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.
sign_message is provided by the COTI MCP Server MCP server (davibauer/coti-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Open source. One binary. Zero dependencies.
npx -y @policylayer/intercept