notification¶

  $client->on(notification => sub ($client, $notification) { ... });

Emitted for every JSON-RPC notification the server sends on the response stream of a request, such as a progress report for a long running tool call.

capabilities¶

  my $capabilities = $client->capabilities;
  $client          = $client->capabilities({elicitation => {}});

Capabilities to declare with every request, defaults to an empty hash reference.

headers¶

  my $headers = $client->headers;
  $client     = $client->headers({Authorization => 'Bearer abc123'});

Extra HTTP headers to send with every request, as a hash reference. Useful for passing an "Authorization" header to an MCP server that requires OAuth bearer authentication. Defaults to an empty hash reference.

name¶

  my $name = $client->name;
  $client  = $client->name('PerlClient');

The name of the client, defaults to "PerlClient".

protocol_version¶

  my $version = $client->protocol_version;
  $client     = $client->protocol_version('2026-07-28');

The protocol version to make requests with, defaults to "PROTOCOL_VERSION" in MCP::Constants. A server rejecting it with an "UnsupportedProtocolVersionError" gets one more chance with the newest version both sides support, and that version is remembered for subsequent requests.

ua¶

  my $ua  = $client->ua;
  $client = $client->ua(Mojo::UserAgent->new);

The user agent used for making HTTP requests, defaults to a new instance of Mojo::UserAgent.

url¶

  my $url  = $client->url;
  $client  = $client->url('http://localhost:3000/mcp');

The URL of the MCP server, defaults to "http://localhost:3000/mcp".

version¶

  my $version = $client->version;
  $client     = $client->version('1.0.0');

The version of the client, defaults to 1.0.0.

build_notification¶

  my $notification = $client->build_notification('method_name', {param1 => 'value1'});

Builds a JSON-RPC notification with the given method name and parameters.

build_request¶

  my $request = $client->build_request('method_name', {param1 => 'value1'});

Builds a JSON-RPC request with the given method name and parameters, adding the "_meta" fields every request has to carry.

call_tool¶

  my $result = $client->call_tool('tool_name');
  my $result = $client->call_tool('tool_name', {arg1 => 'value1'});
  my $result = $client->call_tool('tool_name', {arg1 => 'value1'}, {request_state => $state});

Calls a tool on the MCP server with the specified name and arguments, returning the result.

A result with "resultType" set to "input_required" is returned as-is; gathering the requested input and deciding whether to call again is up to you.

These options are currently available:

input_responses

  input_responses => {confirm => {action => 'accept', content => {ok => \1}}}
    

Responses to the input requests of an earlier "input_required" result, keyed by the same names.

request_state

  request_state => 'eyJ...'
    

The "requestState" of an earlier "input_required" result, passed back verbatim.

discover¶

  my $result = $client->discover;

Discover the protocol versions, capabilities, and instructions of the MCP server.

get_prompt¶

  my $result = $client->get_prompt('prompt_name');
  my $result = $client->get_prompt('prompt_name', {arg1 => 'value1'});
  my $result = $client->get_prompt('prompt_name', {arg1 => 'value1'}, {request_state => $state});

Get a prompt from the MCP server with the specified name and arguments, returning the result. Takes the same options as "call_tool".

list_prompts¶

  my $prompts = $client->list_prompts;

Lists all available prompts on the MCP server.

list_resources¶

  my $resources = $client->list_resources;

Lists all available resources on the MCP server.

list_tools¶

  my $tools = $client->list_tools;

Lists all available tools on the MCP server.

listen¶

  my $bool = $client->listen({toolsListChanged => \1}, sub ($message) {...});

Open a "subscriptions/listen" stream for the requested notification types and block, invoking the callback for every message the server sends, starting with the acknowledgement. Returning a false value from the callback closes the stream. Only servers configured with "streaming => 1" support this.

read_resource¶

  my $result = $client->read_resource('file:///path/to/resource.txt');
  my $result = $client->read_resource('file:///path/to/resource.txt', {request_state => $state});

Reads a resource from the MCP server with the specified URI, returning the result. Takes the same options as "call_tool".

send_request¶

  my $response = $client->send_request($request);

Sends a JSON-RPC request to the MCP server and returns the response, or "undef" if the server accepted it without one.