# Reported issues for pmcp

Pod holds 6 of 6 problems reported by people outside the maintainer team. Issues filed by the project's own owners, members and collaborators are excluded entirely — a maintainer's release checklist is not a warning to a prospective user.

Back to [pmcp](/mcp/pmcp).

## Most discussed

### StdioTransport: stdin EOF disables stdout, dropping responses to already-accepted requests

# StdioTransport: stdin EOF disables stdout, dropping responses to already-accepted requests

## Summary

`StdioTransport` uses a single `closed` flag for two independent streams. Reaching EOF on
**stdin** sets it, and `send()` then refuses every **stdout** write. A client that pipes a
batch of requests and closes stdin — the normal shape of a one-shot MCP session — never
receives the responses to requests the server already accepted and answered.

## Where

`src/shared/stdio.rs` (v2.17.0):

```

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/316) · 2026-07-31 · closed · outside contributor · 0 comments

### wasm support for pmcp-macros

Love that this project supports webassembly though I notice that the [`WasmMcpServer` uses `WasmTool`, `WasmResource` and `WasmPrompt`](https://github.com/paiml/rust-mcp-sdk/blob/9edc4b4974c02f00d7b7d097a03aa401271db8ae/src/server/wasm_server.rs#L328-L358) rather than [`ToolHandler`, `PromptHandler` and `ResourceHandler`](https://github.com/paiml/rust-mcp-sdk/blob/9edc4b4974c02f00d7b7d097a03aa401271db8ae/src/server/mod.rs#L221-L270). I've not spent a ton of time digging into the macro generation

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/278) · 2026-06-11 · open · external user · 0 comments

### fix: .cargo/config.toml has local /mnt/zram/targets path — breaks CI

## Bug

All CI jobs fail with:
```
error: failed to create directory /mnt/zram/targets — Permission denied (os error 13)
```

`.cargo/config.toml` has `target-dir = "/mnt/zram/targets"` committed, which only exists on a local dev machine.

## Five-Whys

1. **Why permission denied?** `/mnt/zram/targets` doesn't exist on GitHub runners.
2. **Why is Cargo using that path?** `.cargo/config.toml` sets `target-dir`.
3. **Why is a local path in the repo?** Developer's zram ramdisk config was committed.

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/222) · 2026-04-05 · closed · outside contributor · 1 comment

### Stdio Transport Non-Compliance with MCP Specification

The stdio transport implementation uses HTTP-style Content-Length header framing instead of the newline-delimited JSON-RPC messages required by the MCP specification. This causes incompatibility with standard MCP clients.

The specification is exacting here:

```

Messages are individual JSON-RPC requests, notifications, or responses.
Messages are delimited by newlines, and MUST NOT contain embedded newlines.

The server MUST NOT write anything to its stdout that is not a valid MCP message.
The 

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/158) · 2026-01-15 · closed · outside contributor · 1 comment

### Stdio example not working

Try example from README.md in the project root. Server started but not respond.

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/116) · 2025-11-27 · open · external user · 0 comments

### Bug: ToolResult not exported from pmcp crate root

# Bug Report: ToolResult not exported from pmcp crate root

## Summary

The `ToolResult` enum is not accessible when importing from `pmcp` crate root, despite being referenced in working examples and documentation. This prevents proper MCP tool implementation when following the documented patterns.

## Environment

- **pmcp version**: 1.3.0 (also tested with 1.2.0)
- **Rust version**: 1.89.0 (2025-06-23 c24e10642)
- **Platform**: Linux 6.8.0-79-lowlatency
- **Cargo features**: `["full", "validat

[Read the thread](https://github.com/paiml/rust-mcp-sdk/issues/37) · 2025-09-08 · closed · outside contributor · 0 comments

## Most recent

The remaining reports are on [the project's issue tracker](https://github.com/paiml/rust-mcp-sdk/issues).