Module: ActionMCP::Server::Resources

Included in:
TransportHandler
Defined in:
lib/action_mcp/server/resources.rb

Instance Method Summary collapse

Instance Method Details

#send_resource_read(id, params) ⇒ Object

Read and return the contents of a resource

Parameters:

  • id (String, Integer) —

    The ID of the request to respond to

  • params (Hash) —

    Parameters specifying which resource to read



47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
 
# File 'lib/action_mcp/server/resources.rb', line 47

def send_resource_read(id, params)
  uri = params["uri"]
  template = ResourceTemplatesRegistry.find_template_for_uri(uri)

  unless template
    error = {
      code: -32_002,
      message: "Resource not found",
      data: { uri: uri }
    }
    send_jsonrpc_response(id, error: error)
    return
  end

  # Check if resource requires consent and if consent is granted
  if template.respond_to?(:requires_consent?) && template.requires_consent? && !session.consent_granted_for?("resource:#{template.name}")
    error = {
      code: -32_002,
      message: "Consent required for resource template '#{template.name}'"
    }
    send_jsonrpc_response(id, error: error)
    return
  end

  unless template.readable_uri?(uri)
    error = {
      code: -32_002,
      message: "Resource not found",
      data: { uri: uri }
    }
    send_jsonrpc_response(id, error: error)
    return
  end

  begin
    # Create template instance and set execution context
    record = template.process(uri)
    unless record
      error = {
        code: -32_002,
        message: "Resource not found",
        data: { uri: uri }
      }
      send_jsonrpc_response(id, error: error)
      return
    end

    record.with_context({ session: session })

    response = record.call

    if response.error?
      send_jsonrpc_response(id, error: response.to_h)
    else
      # Normalize contents to MCP ReadResourceResult shape
      contents = response.contents.map { |c| normalize_read_content(c, uri) }
      send_jsonrpc_response(id, result: { contents: contents })
    end
  rescue StandardError => e
    Rails.logger.error "[MCP Error] #{e.class}: #{e.message}"
    send_jsonrpc_error(id, :internal_error, "Failed to read resource: #{e.message}")
  end
end

#send_resource_templates_list(request_id, params = {}) ⇒ Object

Send list of resource templates to the client

Parameters:

  • request_id (String, Integer) —

    The ID of the request to respond to

  • params (Hash) (defaults to: {}) —

    Optional params including “cursor” for pagination



29
30
31
32
33
34
35
36
37
38
39
40
41
 
# File 'lib/action_mcp/server/resources.rb', line 29

def send_resource_templates_list(request_id, params = {})
  templates = session.registered_resource_templates.map(&:to_h)
  log_resource_templates

  page, next_cursor = paginate(templates, cursor: params["cursor"])

  result = { resourceTemplates: page }
  result[:nextCursor] = next_cursor if next_cursor

  send_jsonrpc_response(request_id, result: result)
rescue Server::CursorError => e
  send_jsonrpc_error(request_id, :invalid_params, e.message)
end

#send_resources_list(request_id, params = {}) ⇒ Object

Send list of concrete resources to the client. Aggregates resources from templates that implement self.list.

Parameters:

  • request_id (String, Integer) —

    The ID of the request to respond to

  • params (Hash) (defaults to: {}) —

    Optional params including “cursor” for pagination



11
12
13
14
15
16
17
18
19
20
21
22
23
 
# File 'lib/action_mcp/server/resources.rb', line 11

def send_resources_list(request_id, params = {})
  all_resources = collect_resources(request_id)
  return unless all_resources # nil means an error was already sent

  page, next_cursor = paginate(all_resources, cursor: params["cursor"])

  result = { resources: page.map(&:to_h) }
  result[:nextCursor] = next_cursor if next_cursor

  send_jsonrpc_response(request_id, result: result)
rescue Server::CursorError => e
  send_jsonrpc_error(request_id, :invalid_params, e.message)
end