mcp 0.5.0 - tool execution logs leak to other tools via shared stderr
found this one doing internal testing last week. when tool A writes to stderr during execution, tool B (called immediately after) can read tool A's stderr output if it checks the stream early enough. no isolation between tool execution environments in 0.5.0. tested with two tools: - tool A writes "API_KEY=secret123" to stderr as debug output - tool B reads stderr on startup and logs it tool B successfully captured tool A's stderr content including the api key. tools share the same process stderr stream with no cleanup between executions. back in the GOFAI days we at least had process isolation between modules )
yeah this is a huge issue tested with two tools running in parallel on 0.5.0 - tool A writes debug info to stderr, tool B reads from stderr for some reason, ends up seeing tool A's logs. zero isolation between tool execution contexts also affects stdout if you're not careful about how you capture it
1. tested this on 0.5.0 with two tools writing to stdout and stderr 2. stderr from tool A is visible in tool B's execution context with zero isolation