github/github-mcp-server · error

failed to unmarshal tools: %w

Error message

failed to unmarshal tools: %w

What it means

Error "failed to unmarshal tools: %w" thrown in github/github-mcp-server.

Source

Thrown at cmd/github-mcp-server/main.go:91

			// it's because viper doesn't handle comma-separated values correctly for env
			// vars when using GetStringSlice.
			// https://github.com/spf13/viper/issues/380
			//
			// Additionally, viper.UnmarshalKey returns an empty slice even when the flag
			// is not set, but we need nil to indicate "use defaults". So we check IsSet first.
			var enabledToolsets []string
			if viper.IsSet("toolsets") {
				if err := viper.UnmarshalKey("toolsets", &enabledToolsets); err != nil {
					return fmt.Errorf("failed to unmarshal toolsets: %w", err)
				}
			}
			// else: enabledToolsets stays nil, meaning "use defaults"

			// Parse tools (similar to toolsets)
			var enabledTools []string
			if viper.IsSet("tools") {
				if err := viper.UnmarshalKey("tools", &enabledTools); err != nil {
					return fmt.Errorf("failed to unmarshal tools: %w", err)
				}
			}

			// Parse excluded tools (similar to tools)
			var excludeTools []string
			if viper.IsSet("exclude_tools") {
				if err := viper.UnmarshalKey("exclude_tools", &excludeTools); err != nil {
					return fmt.Errorf("failed to unmarshal exclude-tools: %w", err)
				}
			}

			// Parse enabled features (similar to toolsets)
			var enabledFeatures []string
			if viper.IsSet("features") {
				if err := viper.UnmarshalKey("features", &enabledFeatures); err != nil {
					return fmt.Errorf("failed to unmarshal features: %w", err)
				}
			}

View on GitHub (pinned to 0ea1f775a7)

When it happens

Trigger: Thrown at cmd/github-mcp-server/main.go:91 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of github/github-mcp-server@0ea1f775a7 (2026-08-15). Data as JSON: /api/errors/66687d739c94565c. Report an issue: GitHub.