MCP Resources

MCP resources are read-only data exposed by a server (files, docs, schemas) — distinct from MCP tools, which take arguments and perform actions. MCPResourceStepDescription fetches a resource and writes it to memory + history, with no tool call.

from mmar_carl import MCPResourceStepDescription, MCPResourceStepConfig, MCPServerConfig

MCPResourceStepDescription(
    number=1,
    title="Load API reference",
    config=MCPResourceStepConfig(
        server=MCPServerConfig(server_name="docs", transport="sse", url="http://docs/sse"),
        resource_uri="docs://api/reference.md",
        output_memory_key="api_docs",
    ),
)

MCPResourceStepConfig

Field	Default	Purpose
server	—	The MCPServerConfig.
resource_uri	—	URI of the resource (e.g. docs://api/reference.md).
output_memory_key	""	When set, stores content at memory[output_namespace][key]. When empty, it’s only in $history[-1] / $metadata.step_N.
output_namespace	"mcp_resource"	Namespace for the write.
timeout	30.0	Seconds.

Read the content back later with $memory.mcp_resource.api_docs (or your chosen key/namespace).

See also

• MCP overview — calling tools.
• Dynamic references — reading the stored content.