Building a Server with the Python SDK

from mcp.server.fastmcp import FastMCP
from mcp.server.fastmcp.prompts import base
from pydantic import Field

mcp = FastMCP("DocumentMCP", log_level="ERROR")

docs = {
    "deposition.md": "This deposition covers the testimony of Angela Smith, P.E.",
    "report.pdf": "The report details the state of a 20m condenser tower.",
    "financials.docx": "These financials outline the project's budget.",
    "plan.md": "The plan outlines the steps for the project's implementation.",
}

@mcp.tool(name="read_doc_contents", description="Read the contents of a document and return it as a string.")
def read_document(doc_id: str = Field(description="Id of the document to read")):
    if doc_id not in docs:
        raise ValueError(f"Doc with id {doc_id} not found")
    return docs[doc_id]

@mcp.tool(name="edit_document", description="Edit a document via exact-match find and replace.")
def edit_document(
    doc_id: str = Field(description="Id of the document that will be edited"),
    old_str: str = Field(description="Text to replace. Must match exactly."),
    new_str: str = Field(description="Replacement text."),
):
    if doc_id not in docs:
        raise ValueError(f"Doc with id {doc_id} not found")
    docs[doc_id] = docs[doc_id].replace(old_str, new_str)

@mcp.resource("docs://documents", mime_type="application/json")
def list_docs() -> list[str]:
    return list(docs.keys())

@mcp.resource("docs://documents/{doc_id}", mime_type="text/plain")
def fetch_doc(doc_id: str) -> str:
    if doc_id not in docs:
        raise ValueError(f"Doc with id {doc_id} not found")
    return docs[doc_id]

if __name__ == "__main__":
    mcp.run(transport="stdio")

# Later, to serve remotely instead:
#   mcp.run(transport="streamable-http")