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When init() is called, mcp-tap monkey-patches each supported SDK. If a library isn’t installed, its patch is silently skipped. Patches never raise exceptions or affect application behavior.

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Supported SDKs

SDKTypeScriptPythonWhat’s patched
Anthropic@anthropic-ai/sdkanthropicMessages.create (sync + async in Python)
OpenAIopenaiopenaiChat.Completions.create (sync + async in Python)
MCP Client@modelcontextprotocol/sdkmcpClient.callTool / ClientSession.call_tool
Composiocomposio-corecomposioComposioToolSet.executeAction / execute_action
HTTP (catch-all)globalThis.fetchhttpxRequests to known AI API hosts

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What gets captured

For LLM requests (Anthropic, OpenAI, HTTP), mcp-tap emits an llm_request parent event with:
  • Model name, system prompt, request messages, response content
  • Token usage (input/output/cache tokens)
  • Thinking/reasoning blocks (if present)
  • Stop reason
  • Latency
For each tool call in the response, a child tool_call event is emitted with the tool name and input arguments, linked to the parent via parent_event_id. For MCP and Composio calls, a tool_call event is emitted with tool name, inputs, output, error (if any), and latency.

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Individual patch functions

Each patch can be applied independently if you don’t want init() to patch everything: 
import { patchAnthropic, patchOpenAI, patchMCP, patchComposio, patchHTTP } from "mcp-tap";

patchAnthropic();  // Patches @anthropic-ai/sdk Messages.create
patchOpenAI();     // Patches openai Chat.Completions.create
patchMCP();        // Patches @modelcontextprotocol/sdk Client.callTool
patchComposio();   // Patches composio-core ComposioToolSet.executeAction
patchHTTP();       // Patches globalThis.fetch for known AI hosts

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Double-counting prevention

When both an SDK patch and the HTTP patch are active, the SDK patch marks a flag (_inSdkPatch in TypeScript, mark_sdk_patch() in Python) during execution. The HTTP patch checks this flag and skips interception when it’s set, preventing the same call from being logged twice.