Add MCP Resources for ROS Metadata etc #205
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- Add resources/ros_metadata.py: Resource for getting all ROS metadata (topics, services, nodes, parameters) - Add resources/robot_specs.py: Resource for listing all available robot specifications - Fix rosapi parameters service: Use /rosapi/get_param_names instead of /rosapi/parameters - Add resources/__init__.py: Register all resources with MCP server - Update server.py: Register MCP resources on startup
stex2005
added
enhancement
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Rationale
Tools are great for operations, but they're not ideal for read-only data that gets accessed frequently. Every tool call is a full round-trip with no caching, and LLMs need to know tool names ahead of time to use them.
Features added
MCP Resources solve this by:
list_resources(), so LLMs can discover what's availableFor example, getting a full ROS system snapshot currently requires calling
get_topics(),get_services(),get_nodes(), andget_parameters()separately. With resources, it's one call toros-mcp://ros-metadata/allthat returns everything, and the client caches it.Implementation
Added two resources:
ros-mcp://ros-metadata/all- Aggregates all ROS system info (topics, services, nodes, parameters, ROS version) in a single JSON response. Handles ROS1/ROS2 differences gracefully.ros-mcp://robot-specs/get_all_robots- Lists available robot specification files for discovery.Both resources are registered in
resources/__init__.pyand automatically loaded on server startup. Also fixed a bug where the metadata resource was calling the non-existent/rosapi/parametersservice - now correctly uses/rosapi/get_param_names.Fully backward compatible - all existing tools remain unchanged. Resources complement tools rather than replace them.
Future Plans
If we agree, I plan to convert simple read-only list operations (like
get_topics(),get_services(),get_nodes()) into resources for better caching and discovery, while keeping parameterized queries (likeget_topic_type(topic),get_parameter(name)) as tools since they require specific inputs and benefit from structured error handling. This will help ROS discovery and introspection while keeping the number of tools limited. At the same time I am planning to merge some tools (inspect + details/type) for better clarity.