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Posted to commits@maka.apache.org by "ser163 (via GitHub)" <gi...@apache.org> on 2026/08/29 17:38:09 UTC
[I] Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object) [maka]
ser163 opened a new issue, #4209:
URL: https://github.com/apache/maka/issues/4209
## Bug Report: Configuring any MCP server crashes Maka (native capability provider requires `tool.parameters instanceof z.ZodType`, but `buildMcpTools` wraps schemas with `ai.jsonSchema()` which returns a plain object)
---
### Summary
Adding **any** stdio MCP server to the workspace `mcp.json` crashes Maka at startup / takes the runtime-host down. The desktop app becomes unusable (all IPC hangs, `execution-candidate-main.js` cannot stay connected) until `mcpServers` is cleared. This affects every MCP server, not a specific one — MCP support is effectively broken in 0.2.0.
### Environment
- App: Maka desktop 0.2.0 (packaged macOS, arm64; CHANGELOG marks 0.2.0 as "Unreleased")
- Electron 43.4.1 / Node 24.18.1
- macOS 26.6
- Trigger: any stdio MCP server (e.g. a 15-line server returning one tool with a JSON-Schema input) registered in `~/Library/Application Support/Maka/workspaces/default/mcp.json` (version 3)
### Root cause
1. `buildMcpTools` (`packages/runtime/src/mcp-tools.ts`) builds each MCP tool with:
```js
parameters: jsonSchema(descriptor.inputSchema),
```
In the bundled `ai` SDK v7, `jsonSchema()` returns a **plain object** wrapper:
```js
{ _type: 'jsonSchema', jsonSchema: <original JSON Schema>, validate: fn }
```
— NOT an instance of `z.ZodType` (verified at runtime: `jsonSchema(...) instanceof z.ZodType === false`, and it has no `_def`/`parse`, so `toJSONSchema` also fails).
2. These tools are handed to the desktop **native capability provider** as the `desktop_mcp` group (`dist/main/runtime-host-boot.js`, `additionalGroups()`).
3. The capability provider validates every tool schema:
```js
// dist/main/runtime-host-native-capabilities.js
function requireZodSchema(tool) {
if (!(tool.parameters instanceof z.ZodType)) {
throw new Error(`Desktop native capability tool has an invalid schema: ${tool.name}`);
}
return tool.parameters;
}
```
Called from both `toolInputSchema()` (capability offer build) and `invokeNativeTool()`.
4. With any MCP tool present, `requireZodSchema` throws → the native capability provider / capability composition fails → runtime-host cannot connect → Maka is effectively down (no crash dialog; app hangs with dead IPC).
### Impact
- Configuring **any** MCP server (stdlib, filesystem, my custom one, etc.) bricks the desktop session until `mcpServers` is emptied.
- User-installed MCP servers are a headline feature — they currently cannot be used at all in 0.2.0.
### Reproduction steps
1. In `~/Library/Application Support/Maka/workspaces/default/mcp.json` (version 3), add any stdio server, e.g.:
```json
{ "version": 3, "mcpServers": { "test": {
"command": "node", "args": ["/path/to/server.mjs"], "protocol": "auto" } } }
```
2. Restart Maka.
3. Observe: `execution-candidate-main.js` fails to stay connected, IPC (skills/memory/settings) hangs; the log shows the capability throw for the MCP tool name.
### Expected behavior
- MCP tools register cleanly and become callable (as the MCP protocol intends), without crashing the capability provider.
### Suggested fix (pick one)
- **A (recommended):** In `buildMcpTools`, convert the MCP JSON Schema into a real zod schema instead of wrapping it with `ai.jsonSchema()` (e.g. a small recursive JSON-Schema→zod converter for object/array/string/number/boolean/enum/required/optional, falling back to `z.unknown()` — MCP servers validate their own args anyway). This makes `tool.parameters instanceof z.ZodType` true and keeps `toJSONSchema()` working.
- **B:** Relax `requireZodSchema` / `toolInputSchema` to accept the `ai` jsonSchema wrapper (or any object with a `.jsonSchema` field) and convert it there.
### Verified workaround
- Keep `mcpServers` empty (`{"version":3,"mcpServers":{}}`) — the app runs fine without MCP servers.
- A local patch implementing fix A (a `mcpSchemaToZod` converter in `mcp-tools.js`) restores MCP servers fully: 5 tools from a custom MCP server registered and were callable without any crash.
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Re: [I] Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object) [maka]
Posted by "ser163 (via GitHub)" <gi...@apache.org>.
ser163 closed issue #4209: Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object)
URL: https://github.com/apache/maka/issues/4209
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Re: [I] Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object) [maka]
Posted by "ser163 (via GitHub)" <gi...@apache.org>.
ser163 commented on issue #4209:
URL: https://github.com/apache/maka/issues/4209#issuecomment-5463901672
Closed: 将改用 Bug 报告表单重新提交以自动附加 `bug` 标签（API 创建无法打标签）。
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Re: [I] Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object) [maka]
Posted by "ying-hua (via GitHub)" <gi...@apache.org>.
ying-hua commented on issue #4209:
URL: https://github.com/apache/maka/issues/4209#issuecomment-5635846929
This looks resolved on current `main` — the underlying defect was tracked as #4591 (closed as completed on 2026-09-04) and fixed by #4490 (commit `9e1ad2ed5`).
Verified against `84255571b`:
- `declaredToolInputSchema()` in `apps/desktop/src/main/runtime-host-native-capabilities.ts:654` now branches on the parameter kind instead of assuming zod:
```ts
const schema = tool.parameters instanceof z.ZodType
? toJSONSchema(tool.parameters, { io: "input", target: "draft-07", ... })
: cloneDeclaredJsonSchema(tool);
```
- `cloneDeclaredJsonSchema()` (line 668) reads `tool.parameters.jsonSchema` and only throws `Desktop native capability tool has an invalid schema` when that value is not a plain object.
- `buildMcpTools()` still passes `parameters: jsonSchema(inputSchema)` (`packages/runtime/src/mcp-tools.ts:146`), which produces exactly that shape, so it takes the non-zod branch and no longer raises.
The follow-ups that widened this path are also merged: #4614 (schema-keyword allowlist) and #4652 (aggregate limits).
@ser163 also noted above that this report would be resubmitted through the bug form, so this one appears to have been left open by accident. Suggest closing as a duplicate of #4591 unless the crash still reproduces on a recent build — happy to re-check if anyone still sees it.
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Re: [I] Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object) [maka]
Posted by "ser163 (via GitHub)" <gi...@apache.org>.
ser163 closed issue #4209: Bug: Configuring any MCP server crashes Maka: native capability provider requires zod tool.parameters but buildMcpTools uses ai.jsonSchema() (plain object)
URL: https://github.com/apache/maka/issues/4209
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