Signals

Signals for the mcpclient app.

These signals report the lifecycle of connections to MCP servers, and of the tool calls and resource reads that LLMs make through them.

Note

Experimental. The MCPClient was designed and coded by Claude Code (Anthropic’s Claude Opus 5.5), with Lawrence McDaniel as co-author. It is experimental, and will be documented.

smarter.apps.mcpclient.signals.mcpclient_called = <django.dispatch.dispatcher.Signal object>

Signal sent when an MCPClient api endpoint is called.

Parameters:

• mcpclient (MCPClient) – The mcpclient instance.

• request (HttpRequest) – The HTTP request object.

• args – Positional arguments.

• kwargs – Keyword arguments.

Example:

mcpclient_called.send(sender=self.__class__, mcpclient=self.mcpclient, request=request, args=args, kwargs=kwargs)

smarter.apps.mcpclient.signals.mcpclient_connected = <django.dispatch.dispatcher.Signal object>

Signal sent when Smarter connects to an MCP server and fetches its catalog.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• catalog (MCPServerCatalog) – What the server reported.

Example:

mcpclient_connected.send(sender=self.__class__, mcpclient=mcpclient, catalog=catalog)

smarter.apps.mcpclient.signals.mcpclient_connection_failed = <django.dispatch.dispatcher.Signal object>

Signal sent when Smarter cannot connect to an MCP server, or fetch its catalog.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• error (str) – A description of the error.

Example:

mcpclient_connection_failed.send(sender=self.__class__, mcpclient=mcpclient, error=str(e))

smarter.apps.mcpclient.signals.mcpclient_resource_read = <django.dispatch.dispatcher.Signal object>

Signal sent when an LLM reads an MCP server’s resource.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• uri (str) – The URI of the resource.

• characters (int) – The length of the content returned to the LLM.

Example:

mcpclient_resource_read.send(sender=self.__class__, mcpclient=mcpclient, uri=uri, characters=1234)

smarter.apps.mcpclient.signals.mcpclient_tool_called = <django.dispatch.dispatcher.Signal object>

Signal sent when an LLM calls an MCP server’s tool, before the call.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• tool_name (str) – The name of the tool, as the server reports it.

• arguments (dict) – The tool’s arguments.

Example:

mcpclient_tool_called.send(sender=self.__class__, mcpclient=mcpclient, tool_name=name, arguments=arguments)

smarter.apps.mcpclient.signals.mcpclient_tool_failed = <django.dispatch.dispatcher.Signal object>

Signal sent when an MCP server’s tool cannot be called, e.g. because the server is unreachable.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• tool_name (str) – The name of the tool.

• error (str) – A description of the error, which is also returned to the LLM.

Example:

mcpclient_tool_failed.send(sender=self.__class__, mcpclient=mcpclient, tool_name=name, error=str(e))

smarter.apps.mcpclient.signals.mcpclient_tool_responded = <django.dispatch.dispatcher.Signal object>

Signal sent when an MCP server’s tool returns a result.

Parameters:

• mcpclient (MCPClient) – The MCPClient.

• tool_name (str) – The name of the tool.

• is_error (bool) – True if the tool reported an error.

• characters (int) – The length of the result returned to the LLM.

Example:

mcpclient_tool_responded.send(
    sender=self.__class__, mcpclient=mcpclient, tool_name=name, is_error=False, characters=1234
)