MCP capability catalog and instructions

Installing this package supplies Fred's internal MCP servers at pod startup through its fred.mcp_catalogs entry point (fred_capability_mcp:load_catalog). The loader uses fred_sdk.resources.mcp; capability construction, composer controls and prompt groups live in fred_sdk.contracts.capability.mcp. The package has no fred-runtime dependency.

The runtime resolves one catalog for transport and capability registration. FRED_MCP_CATALOG_FILE or an existing ./config/mcp_catalog.yaml replaces all packaged servers. Otherwise it combines installed providers with the optional FRED_MCP_EXTERNAL_CATALOG_FILE or ./config/mcp_catalog_external.yaml file. Duplicate server IDs fail startup.

The wheel includes one mcp_catalog.yaml with the three MCPs provided by Fred / Knowledge Flow. Third-party MCP servers are not defined by this package.

Internal HTTP MCPs declare their backend and a path relative to its API:

service: knowledge_flow
path: mcp-tabular

fred_sdk.contracts.services defines FredService and ServiceEndpointsPort. At boot, the runtime passes ConfiguredServiceEndpoints to each catalog loader. Its get_base_url(service) reads ai.knowledge_flow_url or platform.control_plane_url, preserving the configured scheme, host, port and API prefix. For example, https://kf.example:9443/custom/v2/ produces https://kf.example:9443/custom/v2/mcp-tabular. No address is stored in the package catalog. Local document search is supplied by the native document_access capability; the MCP catalog no longer advertises that tool or the unimplemented GitHub adapter. Local tools use capabilities rather than an MCP transport.

External catalogs may use the same references by passing services to the SDK loader, or retain a concrete url. Do not combine service with url. Unknown services, missing addresses and invalid HTTP paths fail catalog loading. SDK-only callers supply their own implementation of the port; no runtime import or network discovery is required.

The wheel also includes prompts/tabular.md, the default pod's tabular instructions.

Deployment-owned catalogs can reference these instructions using:

prompt_file: pkg://fred_capability_mcp/prompts/tabular.md

Inline agent_instructions remains supported. File references also accept absolute paths or paths relative to the catalog. A packaged catalog resolves relative paths within the package, including when imported from a wheel. Declare only one instruction source; unreadable resources fail startup.

fred-agents installs this package locally and in its image; no copied catalog or checkout symlink is needed. The Fred chart mounts an additional external catalog while the installed package supplies its internal servers. Other pods can provide their own MCP catalogs through the SDK/runtime interfaces. No extra selectable wrapper capability is introduced: enabled servers retain their IDs.