| Tool | the object one endpoint compiles to |
| Factories | api_key_tool_factory, oauth_tool_factory, and the builder they return |
| Schema markers | Path, Query, Body, Format, Mode, Case, KeyCase, TransportOverride |
| Semantic types | the shapes a model fills in before a transform encodes them |
| Protobuf types | the google.protobuf well-known types as Pydantic models |
| Credentials | providers, and the subject machinery for many end users |
| OAuth | servers, clients, and the two steps of obtaining a grant |
| Envelopes and pagination | failure inside a 200, and where the cursor lives |
| Transforms | the registry, and the eleven built-in transforms |
| Response handling | trimming a payload before the model reads it |
| Observability and egress | what a call cost, and what the model can see |
| Errors | the exception hierarchy |
| Configuration | configure(), the tuning settings, the environment |
| Command line | charter-mcp |
