docs: add documentation for 19 missing features (SEP-1730 Tier 1)

felixweinberger · felixweinberger · commit e971259b1d5b · 2026-02-19T17:16:44.000Z
Add documentation with examples for all previously undocumented features:

Server (docs/server.md - 260 lines added):
- Tools: audio results, change notifications
- Resources: binary reading, subscribing, unsubscribing
- Prompts: embedded resources, image content, change notifications
- Logging: setting level
- Elicitation: enum values, complete notification

Client (docs/client.md - 109 lines added):
- Roots: listing, change notifications
- SSE transport (legacy client)
- Ping, logging

Protocol (docs/protocol.md - 110 lines added):
- Ping, cancellation, capability negotiation
- Protocol version negotiation, JSON Schema 2020-12

All code snippets verified against SDK source.
diff --git a/docs/client.md b/docs/client.md
@@ -317,6 +317,115 @@ _Full example: [examples/snippets/clients/oauth_client.py](https://github.com/mo
 
 For a complete working example, see [`examples/clients/simple-auth-client/`](examples/clients/simple-auth-client/).
 
+## Roots
+
+### Listing Roots
+
+Clients can provide a `list_roots_callback` so that servers can discover the client's workspace roots (directories, project folders, etc.):
+
+```python
+from mcp import ClientSession, types
+from mcp.shared.context import RequestContext
+
+
+async def handle_list_roots(
+    context: RequestContext[ClientSession, None],
+) -> types.ListRootsResult:
+    """Return the client's workspace roots."""
+    return types.ListRootsResult(
+        roots=[
+            types.Root(uri="file:///home/user/project", name="My Project"),
+            types.Root(uri="file:///home/user/data", name="Data Folder"),
+        ]
+    )
+
+
+# Pass the callback when creating the session
+session = ClientSession(
+    read_stream,
+    write_stream,
+    list_roots_callback=handle_list_roots,
+)
+```
+
+When a `list_roots_callback` is provided, the client automatically declares the `roots` capability (with `listChanged=True`) during initialization.
+
+### Roots Change Notifications
+
+When the client's workspace roots change (e.g., a folder is added or removed), notify the server:
+
+```python
+# After roots change, notify the server
+await session.send_roots_list_changed()
+```
+
+## SSE Transport (Legacy)
+
+For servers that use the older SSE transport, use `sse_client()` from `mcp.client.sse`:
+
+```python
+import asyncio
+
+from mcp import ClientSession
+from mcp.client.sse import sse_client
+
+
+async def main():
+    async with sse_client("http://localhost:8000/sse") as (read_stream, write_stream):
+        async with ClientSession(read_stream, write_stream) as session:
+            await session.initialize()
+
+            tools = await session.list_tools()
+            print(f"Available tools: {[t.name for t in tools.tools]}")
+
+
+asyncio.run(main())
+```
+
+The `sse_client()` function accepts optional `headers`, `timeout`, `sse_read_timeout`, and `auth` parameters. The SSE transport is considered legacy; prefer [Streamable HTTP](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http) for new servers.
+
+## Ping
+
+Send a ping to verify the server is responsive:
+
+```python
+# After session.initialize()
+result = await session.send_ping()
+# Returns EmptyResult on success; raises on timeout
+```
+
+## Logging
+
+### Receiving Log Messages
+
+Pass a `logging_callback` to receive log messages from the server:
+
+```python
+from mcp import ClientSession, types
+
+
+async def handle_log(params: types.LoggingMessageNotificationParams) -> None:
+    """Handle log messages from the server."""
+    print(f"[{params.level}] {params.data}")
+
+
+session = ClientSession(
+    read_stream,
+    write_stream,
+    logging_callback=handle_log,
+)
+```
+
+### Setting the Server Log Level
+
+Request that the server change its minimum log level:
+
+```python
+await session.set_logging_level("debug")
+```
+
+The `level` parameter is a `LoggingLevel` string: `"debug"`, `"info"`, `"notice"`, `"warning"`, `"error"`, `"critical"`, `"alert"`, or `"emergency"`.
+
 ## Parsing Tool Results
 
 When calling tools through MCP, the `CallToolResult` object contains the tool's response in a structured format. Understanding how to parse this result is essential for properly handling tool outputs.
diff --git a/docs/protocol.md b/docs/protocol.md
@@ -24,6 +24,116 @@ MCP servers declare capabilities during initialization:
 | `logging`    | -                            | Server logging configuration       |
 | `completions`| -                            | Argument completion suggestions    |
 
+## Ping
+
+Both clients and servers can send ping requests to check that the other side is responsive:
+
+```python
+# From a client
+result = await session.send_ping()
+
+# From a server (via ServerSession)
+result = await server_session.send_ping()
+```
+
+Both return an `EmptyResult` on success. If the remote side does not respond within the session timeout, an exception is raised.
+
+## Cancellation
+
+Either side can cancel a previously-issued request by sending a `CancelledNotification`:
+
+```python
+import mcp.types as types
+
+# Send a cancellation notification
+await session.send_notification(
+    types.ClientNotification(
+        types.CancelledNotification(
+            params=types.CancelledNotificationParams(
+                requestId="request-id-to-cancel",
+                reason="User navigated away",
+            )
+        )
+    )
+)
+```
+
+The `CancelledNotificationParams` fields:
+
+- `requestId` (optional): The ID of the request to cancel. Required for non-task cancellations.
+- `reason` (optional): A human-readable string describing why the request was cancelled.
+
+## Capability Negotiation
+
+During initialization, the client and server exchange capability declarations. The Python SDK automatically declares capabilities based on which callbacks and handlers are registered:
+
+**Client capabilities** (auto-declared when callbacks are provided):
+
+- `sampling` -- declared when `sampling_callback` is passed to `ClientSession`
+- `roots` -- declared when `list_roots_callback` is passed to `ClientSession`
+- `elicitation` -- declared when `elicitation_callback` is passed to `ClientSession`
+
+**Server capabilities** (auto-declared when handlers are registered):
+
+- `prompts` -- declared when a `list_prompts` handler is registered
+- `resources` -- declared when a `list_resources` handler is registered
+- `tools` -- declared when a `list_tools` handler is registered
+- `logging` -- declared when a `set_logging_level` handler is registered
+- `completions` -- declared when a `completion` handler is registered
+
+After initialization, clients can inspect server capabilities:
+
+```python
+capabilities = session.get_server_capabilities()
+if capabilities and capabilities.tools:
+    tools = await session.list_tools()
+```
+
+## Protocol Version Negotiation
+
+The SDK defines `LATEST_PROTOCOL_VERSION` and `SUPPORTED_PROTOCOL_VERSIONS` in `mcp.shared.version`:
+
+```python
+from mcp.shared.version import LATEST_PROTOCOL_VERSION, SUPPORTED_PROTOCOL_VERSIONS
+
+# LATEST_PROTOCOL_VERSION is the version the SDK advertises during initialization
+# SUPPORTED_PROTOCOL_VERSIONS lists all versions the SDK can work with
+```
+
+During initialization, the client sends `LATEST_PROTOCOL_VERSION`. If the server responds with a version not in `SUPPORTED_PROTOCOL_VERSIONS`, the client raises a `RuntimeError`. This ensures both sides agree on a compatible protocol version before exchanging messages.
+
+## JSON Schema (2020-12)
+
+MCP uses [JSON Schema 2020-12](https://json-schema.org/draft/2020-12) for tool input schemas, output schemas, and elicitation schemas. When using Pydantic models, schemas are generated automatically via `model_json_schema()`:
+
+```python
+from pydantic import BaseModel, Field
+
+
+class SearchParams(BaseModel):
+    query: str = Field(description="Search query string")
+    max_results: int = Field(default=10, description="Maximum results to return")
+
+
+# Pydantic generates a JSON Schema 2020-12 compatible schema:
+schema = SearchParams.model_json_schema()
+# {
+#     "properties": {
+#         "query": {"description": "Search query string", "type": "string"},
+#         "max_results": {
+#             "default": 10,
+#             "description": "Maximum results to return",
+#             "type": "integer",
+#         },
+#     },
+#     "required": ["query"],
+#     "title": "SearchParams",
+#     "type": "object",
+# }
+```
+
+For FastMCP tools, input schemas are derived automatically from function signatures. For structured output, the output schema is derived from the return type annotation.
+
 ## Pagination
 
 For pagination details, see:
diff --git a/docs/server.md b/docs/server.md
