refactor: replace lowlevel Server decorators with on_* constructor kwargs (#1985)
This commit is contained in:
Max Isbey
GitHub
parent
d6d3ad9a7c
commit
0a22a9dc33
1 changed files with 3563 additions and 5481 deletions
|
|
@ -1,17 +1,19 @@
|
|||
"""Simple MCP server demonstrating pagination for tools, resources, and prompts.
|
||||
|
||||
This example shows how to use the paginated decorators to handle large lists
|
||||
of items that need to be split across multiple pages.
|
||||
This example shows how to implement pagination with the low-level server API
|
||||
to handle large lists of items that need to be split across multiple pages.
|
||||
"""
|
||||
|
||||
from typing import Any
|
||||
from typing import TypeVar
|
||||
|
||||
import anyio
|
||||
import click
|
||||
from mcp import types
|
||||
from mcp.server.lowlevel import Server
|
||||
from mcp.server import Server, ServerRequestContext
|
||||
from starlette.requests import Request
|
||||
|
||||
T = TypeVar("T")
|
||||
|
||||
# Sample data - in real scenarios, this might come from a database
|
||||
SAMPLE_TOOLS = [
|
||||
types.Tool(
|
||||
|
|
@ -44,6 +46,102 @@ SAMPLE_PROMPTS = [
|
|||
]
|
||||
|
||||
|
||||
def _paginate(cursor: str | None, items: list[T], page_size: int) -> tuple[list[T], str | None]:
|
||||
"""Helper to paginate a list of items given a cursor."""
|
||||
if cursor is not None:
|
||||
try:
|
||||
start_idx = int(cursor)
|
||||
except (ValueError, TypeError):
|
||||
return [], None
|
||||
else:
|
||||
start_idx = 0
|
||||
|
||||
page = items[start_idx : start_idx + page_size]
|
||||
next_cursor = str(start_idx + page_size) if start_idx + page_size < len(items) else None
|
||||
return page, next_cursor
|
||||
|
||||
|
||||
# Paginated list_tools - returns 5 tools per page
|
||||
async def handle_list_tools(
|
||||
ctx: ServerRequestContext, params: types.PaginatedRequestParams | None
|
||||
) -> types.ListToolsResult:
|
||||
cursor = params.cursor if params is not None else None
|
||||
page, next_cursor = _paginate(cursor, SAMPLE_TOOLS, page_size=5)
|
||||
return types.ListToolsResult(tools=page, next_cursor=next_cursor)
|
||||
|
||||
|
||||
# Paginated list_resources - returns 10 resources per page
|
||||
async def handle_list_resources(
|
||||
ctx: ServerRequestContext, params: types.PaginatedRequestParams | None
|
||||
) -> types.ListResourcesResult:
|
||||
cursor = params.cursor if params is not None else None
|
||||
page, next_cursor = _paginate(cursor, SAMPLE_RESOURCES, page_size=10)
|
||||
return types.ListResourcesResult(resources=page, next_cursor=next_cursor)
|
||||
|
||||
|
||||
# Paginated list_prompts - returns 7 prompts per page
|
||||
async def handle_list_prompts(
|
||||
ctx: ServerRequestContext, params: types.PaginatedRequestParams | None
|
||||
) -> types.ListPromptsResult:
|
||||
cursor = params.cursor if params is not None else None
|
||||
page, next_cursor = _paginate(cursor, SAMPLE_PROMPTS, page_size=7)
|
||||
return types.ListPromptsResult(prompts=page, next_cursor=next_cursor)
|
||||
|
||||
|
||||
async def handle_call_tool(ctx: ServerRequestContext, params: types.CallToolRequestParams) -> types.CallToolResult:
|
||||
# Find the tool in our sample data
|
||||
tool = next((t for t in SAMPLE_TOOLS if t.name == params.name), None)
|
||||
if not tool:
|
||||
raise ValueError(f"Unknown tool: {params.name}")
|
||||
|
||||
return types.CallToolResult(
|
||||
content=[
|
||||
types.TextContent(
|
||||
type="text",
|
||||
text=f"Called tool '{params.name}' with arguments: {params.arguments}",
|
||||
)
|
||||
]
|
||||
)
|
||||
|
||||
|
||||
async def handle_read_resource(
|
||||
ctx: ServerRequestContext, params: types.ReadResourceRequestParams
|
||||
) -> types.ReadResourceResult:
|
||||
resource = next((r for r in SAMPLE_RESOURCES if r.uri == str(params.uri)), None)
|
||||
if not resource:
|
||||
raise ValueError(f"Unknown resource: {params.uri}")
|
||||
|
||||
return types.ReadResourceResult(
|
||||
contents=[
|
||||
types.TextResourceContents(
|
||||
uri=str(params.uri),
|
||||
text=f"Content of {resource.name}: This is sample content for the resource.",
|
||||
mime_type="text/plain",
|
||||
)
|
||||
]
|
||||
)
|
||||
|
||||
|
||||
async def handle_get_prompt(ctx: ServerRequestContext, params: types.GetPromptRequestParams) -> types.GetPromptResult:
|
||||
prompt = next((p for p in SAMPLE_PROMPTS if p.name == params.name), None)
|
||||
if not prompt:
|
||||
raise ValueError(f"Unknown prompt: {params.name}")
|
||||
|
||||
message_text = f"This is the prompt '{params.name}'"
|
||||
if params.arguments:
|
||||
message_text += f" with arguments: {params.arguments}"
|
||||
|
||||
return types.GetPromptResult(
|
||||
description=prompt.description,
|
||||
messages=[
|
||||
types.PromptMessage(
|
||||
role="user",
|
||||
content=types.TextContent(type="text", text=message_text),
|
||||
)
|
||||
],
|
||||
)
|
||||
|
||||
|
||||
@click.command()
|
||||
@click.option("--port", default=8000, help="Port to listen on for SSE")
|
||||
@click.option(
|
||||
|
|
@ -53,142 +151,15 @@ SAMPLE_PROMPTS = [
|
|||
help="Transport type",
|
||||
)
|
||||
def main(port: int, transport: str) -> int:
|
||||
app = Server("mcp-simple-pagination")
|
||||
|
||||
# Paginated list_tools - returns 5 tools per page
|
||||
@app.list_tools()
|
||||
async def list_tools_paginated(request: types.ListToolsRequest) -> types.ListToolsResult:
|
||||
page_size = 5
|
||||
|
||||
cursor = request.params.cursor if request.params is not None else None
|
||||
if cursor is None:
|
||||
# First page
|
||||
start_idx = 0
|
||||
else:
|
||||
# Parse cursor to get the start index
|
||||
try:
|
||||
start_idx = int(cursor)
|
||||
except (ValueError, TypeError):
|
||||
# Invalid cursor, return empty
|
||||
return types.ListToolsResult(tools=[], next_cursor=None)
|
||||
|
||||
# Get the page of tools
|
||||
page_tools = SAMPLE_TOOLS[start_idx : start_idx + page_size]
|
||||
|
||||
# Determine if there are more pages
|
||||
next_cursor = None
|
||||
if start_idx + page_size < len(SAMPLE_TOOLS):
|
||||
next_cursor = str(start_idx + page_size)
|
||||
|
||||
return types.ListToolsResult(tools=page_tools, next_cursor=next_cursor)
|
||||
|
||||
# Paginated list_resources - returns 10 resources per page
|
||||
@app.list_resources()
|
||||
async def list_resources_paginated(
|
||||
request: types.ListResourcesRequest,
|
||||
) -> types.ListResourcesResult:
|
||||
page_size = 10
|
||||
|
||||
cursor = request.params.cursor if request.params is not None else None
|
||||
if cursor is None:
|
||||
# First page
|
||||
start_idx = 0
|
||||
else:
|
||||
# Parse cursor to get the start index
|
||||
try:
|
||||
start_idx = int(cursor)
|
||||
except (ValueError, TypeError):
|
||||
# Invalid cursor, return empty
|
||||
return types.ListResourcesResult(resources=[], next_cursor=None)
|
||||
|
||||
# Get the page of resources
|
||||
page_resources = SAMPLE_RESOURCES[start_idx : start_idx + page_size]
|
||||
|
||||
# Determine if there are more pages
|
||||
next_cursor = None
|
||||
if start_idx + page_size < len(SAMPLE_RESOURCES):
|
||||
next_cursor = str(start_idx + page_size)
|
||||
|
||||
return types.ListResourcesResult(resources=page_resources, next_cursor=next_cursor)
|
||||
|
||||
# Paginated list_prompts - returns 7 prompts per page
|
||||
@app.list_prompts()
|
||||
async def list_prompts_paginated(
|
||||
request: types.ListPromptsRequest,
|
||||
) -> types.ListPromptsResult:
|
||||
page_size = 7
|
||||
|
||||
cursor = request.params.cursor if request.params is not None else None
|
||||
if cursor is None:
|
||||
# First page
|
||||
start_idx = 0
|
||||
else:
|
||||
# Parse cursor to get the start index
|
||||
try:
|
||||
start_idx = int(cursor)
|
||||
except (ValueError, TypeError):
|
||||
# Invalid cursor, return empty
|
||||
return types.ListPromptsResult(prompts=[], next_cursor=None)
|
||||
|
||||
# Get the page of prompts
|
||||
page_prompts = SAMPLE_PROMPTS[start_idx : start_idx + page_size]
|
||||
|
||||
# Determine if there are more pages
|
||||
next_cursor = None
|
||||
if start_idx + page_size < len(SAMPLE_PROMPTS):
|
||||
next_cursor = str(start_idx + page_size)
|
||||
|
||||
return types.ListPromptsResult(prompts=page_prompts, next_cursor=next_cursor)
|
||||
|
||||
# Implement call_tool handler
|
||||
@app.call_tool()
|
||||
async def call_tool(name: str, arguments: dict[str, Any]) -> list[types.ContentBlock]:
|
||||
# Find the tool in our sample data
|
||||
tool = next((t for t in SAMPLE_TOOLS if t.name == name), None)
|
||||
if not tool:
|
||||
raise ValueError(f"Unknown tool: {name}")
|
||||
|
||||
# Simple mock response
|
||||
return [
|
||||
types.TextContent(
|
||||
type="text",
|
||||
text=f"Called tool '{name}' with arguments: {arguments}",
|
||||
)
|
||||
]
|
||||
|
||||
# Implement read_resource handler
|
||||
@app.read_resource()
|
||||
async def read_resource(uri: str) -> str:
|
||||
# Find the resource in our sample data
|
||||
resource = next((r for r in SAMPLE_RESOURCES if r.uri == uri), None)
|
||||
if not resource:
|
||||
raise ValueError(f"Unknown resource: {uri}")
|
||||
|
||||
# Return a simple string - the decorator will convert it to TextResourceContents
|
||||
return f"Content of {resource.name}: This is sample content for the resource."
|
||||
|
||||
# Implement get_prompt handler
|
||||
@app.get_prompt()
|
||||
async def get_prompt(name: str, arguments: dict[str, str] | None) -> types.GetPromptResult:
|
||||
# Find the prompt in our sample data
|
||||
prompt = next((p for p in SAMPLE_PROMPTS if p.name == name), None)
|
||||
if not prompt:
|
||||
raise ValueError(f"Unknown prompt: {name}")
|
||||
|
||||
# Simple mock response
|
||||
message_text = f"This is the prompt '{name}'"
|
||||
if arguments:
|
||||
message_text += f" with arguments: {arguments}"
|
||||
|
||||
return types.GetPromptResult(
|
||||
description=prompt.description,
|
||||
messages=[
|
||||
types.PromptMessage(
|
||||
role="user",
|
||||
content=types.TextContent(type="text", text=message_text),
|
||||
)
|
||||
],
|
||||
)
|
||||
app = Server(
|
||||
"mcp-simple-pagination",
|
||||
on_list_tools=handle_list_tools,
|
||||
on_list_resources=handle_list_resources,
|
||||
on_list_prompts=handle_list_prompts,
|
||||
on_call_tool=handle_call_tool,
|
||||
on_read_resource=handle_read_resource,
|
||||
on_get_prompt=handle_get_prompt,
|
||||
)
|
||||
|
||||
if transport == "sse":
|
||||
from mcp.server.sse import SseServerTransport
|
||||
|
|
|
|||
Loading…
Reference in a new issue