Troubleshooting

generate skips my action with a warning about an MCP tool

Cause

The tool name on the MCP server doesn’t match what the action’s frontmatter declared.

Fix

Run generate with the server reachable. The warning names the server and the tool that failed to resolve — correct the name in mcpTools, or add the tool to the server.

Could not find an mdlang config file

Cause

The runtime expects mdlang.config.{ts,mts,js,mjs} in the directory you passed, or in process.cwd().

Fix

Point --cwd at the right directory, or move the config. Projects created before the rename can still use backend.config.* and BACKEND.md.

Invalid arguments for action "x"

Cause

Your payload didn’t match the action’s declared args.

Fix

The message lists each failing field. Check types and required flags in the action’s frontmatter — this fires before the model runs, so nothing was spent.

Action did not produce a structured response

Cause

The model returned text that didn’t match the declared output schema.

Fix

Tighten the action’s instruction so it states which fields to fill, or simplify the output shape. Deeply nested outputs are the usual culprit.

Cannot find module './actions/generated/…' after bundling

Cause

You’re on the runAction path, which resolves from disk at call time.

Fix

Import the generated action() wrapper instead. It uses static imports and survives bundling. See Programmatic API.