[github-actions]

Purpose

Landing pinned bub-mcp==0.3.0 because every later release defers remote MCP tools: a configured server's mcp_<server>_<tool> stopped being callable by name. This adopts the deferred behavior and moves the pin to bub-mcp==0.4.0, which #78 listed as the alternative to freezing MCP behavior.

• Bump bub-mcp to 0.4.0 and bind the renamed MCPManager to BubAgent in landing.mcp.connected_tools.
• Render the deferred tool list in Landing's system prompt. BubAgent.prepare_tools exposes tool_describe for deferred tools, but Landing replaces the agent's prompt sections with its own, so the SDK's <deferred_tools> section was missing and the model never learned which server tools it could load. A probe of the first model request showed tool_describe offered with no deferred list; after the change the same request carries - mcp_evidence_record under <deferred_tools>.
• Update tests/test_mcp.py so each task loads the tool with tool_describe before calling it.
• Document loading on demand in docs/reference/configuration.md and docs/guides/mcp.md, including mcp.deferred_tools: false as the way to keep direct tools.

Closes #78.

Validation

• uv run python -m pytest — 136 passed. tests/test_mcp.py covers CLI configuration selection, mode permissions, workspace switching, cancellation, and a missing explicit config, all through the load-then-call path.
• Removing the tool_describe step from test_cli_uses_selected_mcp_configuration[project] makes it fail with no receipt written, so the passing tests do depend on the tool being loaded, not on a direct call.
• uv run ty check — All checks passed.
• uv run pre-commit run --all-files — passed.
• make docs-test — No issues found.
• A one-off probe with mcp: deferred_tools: false in Landing YAML still offers the server tool directly and records a direct call, confirming the documented escape hatch.

Compatibility

Model-facing behavior changes: server tools no longer appear in the tool list until the model loads them with tool_describe, which the task prompt now lists. Mode allowed_tools/excluded_tools still filter before loading, so excluded server tools are neither listed nor loadable. Configure native mcp.deferred_tools: false to keep the previous direct-tool behavior. No CLI, HTTP, or stored-data changes.

AI assistance

Written by Landing's fixer mode on bub-mcp 0.4.0 / Bub 0.6.1 with the model provider recorded by the runner; the delegated maintainer decision came from #78.

[github-actions]

No blocking findings.

The deferred-tool path works through the real runtime: with a workspace .agents/mcp.json, the first model request offers tool_describe with - mcp_evidence_record under <deferred_tools>, the load-then-call sequence records the evidence, a mode excluded_tools entry for that server tool removes both the listing and tool_describe, and the documented mcp: deferred_tools: false escape hatch in Landing YAML puts mcp_evidence_record back in the request's tool list with no deferred section.