Troubleshooting

A GPUI shape is not compatible with a value

Declare value = T or values(...), publish compatibility through value binding, or implement both ComponentShapeFor<T> and GpuiComponentShapeFor<T>.

A consumer rejects a hand-written GPUI shape

If the error names DeclaredGpuiComponentShape, the consumer requires a macro-declared shape. Use the derive or component_shape! so that marker is generated, then rerun the consumer’s Cargo check.

A derive cannot find component-shape-mcp

Use the normal crate name or an unambiguous facade re-export. Add #[mcp(crate = path::to::mcp)] for a renamed crate or when multiple facades make inference ambiguous.

A tool input schema is rejected

Tool inputs need a top-level object schema. Derive McpToolInput for a named argument struct. Use scalar, list, or other schemas only for nested fields and tool outputs.

An argument is reported as unknown

Match the deserialize-facing serde name or one of its aliases. In a custom untyped handler, consume every supported field before calling McpArguments::finish().

A successful output fails validation

Return structured_content that matches the declared output schema. Keep handler failures as error results with a structured error object.