Hello world project errors when built by Prefect Horizon #3184
Description
Description
Prefect Horizon will not deploy the "hello world" project from the getting started guide. The build log's #9 fastmcp inspect -f fastmcp -o log.json "server.py:mcp" succeeds locally.
# Server log
2026-02-13 21:27:41.578000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in <module>
2026-02-13 21:27:41.579000 from key_value.shared.errors.wrappers import (
2026-02-13 21:27:41.579000 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py)
# Build log
2026-02-13T21:27:07.912Z #9 [5/5] RUN fastmcp inspect -f fastmcp -o /tmp/server-info.json "/app/server.py:mcp" || echo '{"error": "Failed to inspect MCP tools"}' > /tmp/server-info.json
2026-02-13T21:27:09.932Z #9 2.158 Traceback (most recent call last):
...
2026-02-13T21:27:11.957Z #9 2.159 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in <module>
2026-02-13T21:27:11.957Z #9 2.159 from key_value.shared.errors.wrappers import (
2026-02-13T21:27:11.957Z #9 2.160 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py)
2026-02-13T21:27:11.957Z #9 DONE 2.4s
...
2026-02-13T21:27:52.736Z ❌ Pre-flight check failed - your MCP server may have startup issues. Check the server logs for detailed error information.
Sorry for the pastes; GitHub's file upload appears to be experiencing an issue.
Build 0058961c
``` 2026-02-13T21:26:04.969Z 🚀 Initializing build environment 2026-02-13T21:26:06.969Z 🌐 Setting up network 2026-02-13T21:26:08.969Z 📦 Preparing dependencies 2026-02-13T21:26:10.969Z ⚡ Inspecting MCP code 2026-02-13T21:26:12.969Z 🔧 Preparing application build 2026-02-13T21:26:14.969Z 📋 Setting up build checks 2026-02-13T21:26:16.969Z 🎯 Initializing encrypted variables 2026-02-13T21:26:18.969Z ✨ Optimizing bundle size 2026-02-13T21:26:20.969Z 🔍 Inspecting manifest 2026-02-13T21:26:22.969Z 🎉 Finalizing build setup 2026-02-13T21:26:07.397Z 🚀 Build started for deployment: mango-test 2026-02-13T21:26:09.879Z ⚙️ Build configuration: 2026-02-13T21:26:09.879Z • Repository: https://github.com/importRyan/mango-test-mcp 2026-02-13T21:26:09.879Z • Entrypoint: server.py:mcp 2026-02-13T21:26:09.879Z • Git SHA: 79298498 2026-02-13T21:26:09.879Z • Billing type: HOBBY 2026-02-13T21:26:09.879Z • Environment variables: none 2026-02-13T21:26:09.879Z 📦 Auto-detecting Python dependencies (will look for pyproject.toml, then requirements.txt)... 2026-02-13T21:26:43.666Z n=0 2026-02-13T21:26:43.666Z max=3 2026-02-13T21:26:43.666Z delay="${RETRY_INITIAL_DELAY:-5}" 2026-02-13T21:26:43.666Z while true; do 2026-02-13T21:26:43.666Z "$@" && break || { 2026-02-13T21:26:43.666Z n=$((n+1)) 2026-02-13T21:26:43.666Z if [ $n -ge $max ]; then 2026-02-13T21:26:43.666Z echo "Failed after $max attempts" 2026-02-13T21:26:43.666Z exit 1 2026-02-13T21:26:43.666Z fi 2026-02-13T21:26:43.666Z echo "Attempt $n/$max failed, retrying in ${delay}s..." 2026-02-13T21:26:43.666Z sleepServer log
``` 2026-02-13 21:27:41.291000 Traceback (most recent call last): 2026-02-13 21:27:41.291000 File "/usr/local/bin/fastmcp", line 4, in 2026-02-13 21:27:41.292000 from fastmcp.cli import app 2026-02-13 21:27:41.292000 File "/usr/local/lib/python3.12/site-packages/fastmcp/__init__.py", line 15, in 2026-02-13 21:27:41.385000 from fastmcp.server.server import FastMCP 2026-02-13 21:27:41.385000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/__init__.py", line 1, in 2026-02-13 21:27:41.474000 from .context import Context 2026-02-13 21:27:41.474000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/context.py", line 28, in 2026-02-13 21:27:41.475000 from fastmcp.resources.resource import ResourceResult 2026-02-13 21:27:41.475000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/__init__.py", line 1, in 2026-02-13 21:27:41.574000 from .function_resource import FunctionResource, resource 2026-02-13 21:27:41.574000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/function_resource.py", line 17, in 2026-02-13 21:27:41.575000 from fastmcp.resources.resource import Resource, ResourceResult 2026-02-13 21:27:41.575000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/resource.py", line 32, in 2026-02-13 21:27:41.576000 from fastmcp.server.auth.authorization import AuthCheck 2026-02-13 21:27:41.576000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/__init__.py", line 17, in 2026-02-13 21:27:41.576000 from .oauth_proxy import OAuthProxy 2026-02-13 21:27:41.576000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/__init__.py", line 10, in 2026-02-13 21:27:41.576000 from fastmcp.server.auth.oauth_proxy.proxy import OAuthProxy 2026-02-13 21:27:41.576000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/proxy.py", line 32, in 2026-02-13 21:27:41.577000 from key_value.aio.adapters.pydantic import PydanticAdapter 2026-02-13 21:27:41.577000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/__init__.py", line 1, in 2026-02-13 21:27:41.577000 from key_value.aio.adapters.base_model import BaseModelAdapter 2026-02-13 21:27:41.577000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/__init__.py", line 1, in 2026-02-13 21:27:41.577000 from key_value.aio.adapters.base_model.adapter import BaseModelAdapter 2026-02-13 21:27:41.577000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/adapter.py", line 7, in 2026-02-13 21:27:41.577000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:41.577000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/__init__.py", line 1, in 2026-02-13 21:27:41.577000 from key_value.aio.adapters.pydantic.adapter import PydanticAdapter 2026-02-13 21:27:41.577000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/adapter.py", line 8, in 2026-02-13 21:27:41.578000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:41.578000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/base.py", line 11, in 2026-02-13 21:27:41.578000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:41.578000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/__init__.py", line 18, in 2026-02-13 21:27:41.578000 from key_value.shared.managed_entry import ManagedEntry 2026-02-13 21:27:41.578000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/managed_entry.py", line 16, in 2026-02-13 21:27:41.578000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:41.578000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in 2026-02-13 21:27:41.579000 from key_value.shared.errors.wrappers import ( 2026-02-13 21:27:41.579000 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py) 2026-02-13 21:27:43.649000 Traceback (most recent call last): 2026-02-13 21:27:43.649000 File "/usr/local/bin/fastmcp", line 4, in 2026-02-13 21:27:43.650000 from fastmcp.cli import app 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/__init__.py", line 15, in 2026-02-13 21:27:43.650000 from fastmcp.server.server import FastMCP 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/__init__.py", line 1, in 2026-02-13 21:27:43.650000 from .context import Context 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/context.py", line 28, in 2026-02-13 21:27:43.650000 from fastmcp.resources.resource import ResourceResult 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/__init__.py", line 1, in 2026-02-13 21:27:43.650000 from .function_resource import FunctionResource, resource 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/function_resource.py", line 17, in 2026-02-13 21:27:43.650000 from fastmcp.resources.resource import Resource, ResourceResult 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/resource.py", line 32, in 2026-02-13 21:27:43.650000 from fastmcp.server.auth.authorization import AuthCheck 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/__init__.py", line 17, in 2026-02-13 21:27:43.650000 from .oauth_proxy import OAuthProxy 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/__init__.py", line 10, in 2026-02-13 21:27:43.650000 from fastmcp.server.auth.oauth_proxy.proxy import OAuthProxy 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/proxy.py", line 32, in 2026-02-13 21:27:43.650000 from key_value.aio.adapters.pydantic import PydanticAdapter 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/__init__.py", line 1, in 2026-02-13 21:27:43.650000 from key_value.aio.adapters.base_model import BaseModelAdapter 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/__init__.py", line 1, in 2026-02-13 21:27:43.650000 from key_value.aio.adapters.base_model.adapter import BaseModelAdapter 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/adapter.py", line 7, in 2026-02-13 21:27:43.650000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:43.650000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/__init__.py", line 1, in 2026-02-13 21:27:43.650000 from key_value.aio.adapters.pydantic.adapter import PydanticAdapter 2026-02-13 21:27:43.651000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/adapter.py", line 8, in 2026-02-13 21:27:43.651000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:43.651000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/base.py", line 11, in 2026-02-13 21:27:43.651000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:43.651000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/__init__.py", line 18, in 2026-02-13 21:27:43.651000 from key_value.shared.managed_entry import ManagedEntry 2026-02-13 21:27:43.651000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/managed_entry.py", line 16, in 2026-02-13 21:27:43.651000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:43.651000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in 2026-02-13 21:27:43.651000 from key_value.shared.errors.wrappers import ( 2026-02-13 21:27:43.651000 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py) 2026-02-13 21:27:44.010000 RequestId: 08dc1707-9d5f-4243-96c7-c94b0f17e4dd Error: Runtime exited with error: exit status 1 Runtime.ExitError 2026-02-13 21:27:48.072000 Traceback (most recent call last): 2026-02-13 21:27:48.072000 File "/usr/local/bin/fastmcp", line 4, in 2026-02-13 21:27:48.072000 from fastmcp.cli import app 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/__init__.py", line 15, in 2026-02-13 21:27:48.072000 from fastmcp.server.server import FastMCP 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/__init__.py", line 1, in 2026-02-13 21:27:48.072000 from .context import Context 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/context.py", line 28, in 2026-02-13 21:27:48.072000 from fastmcp.resources.resource import ResourceResult 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/__init__.py", line 1, in 2026-02-13 21:27:48.072000 from .function_resource import FunctionResource, resource 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/function_resource.py", line 17, in 2026-02-13 21:27:48.072000 from fastmcp.resources.resource import Resource, ResourceResult 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/resource.py", line 32, in 2026-02-13 21:27:48.072000 from fastmcp.server.auth.authorization import AuthCheck 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/__init__.py", line 17, in 2026-02-13 21:27:48.072000 from .oauth_proxy import OAuthProxy 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/__init__.py", line 10, in 2026-02-13 21:27:48.072000 from fastmcp.server.auth.oauth_proxy.proxy import OAuthProxy 2026-02-13 21:27:48.072000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/proxy.py", line 32, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.pydantic import PydanticAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/__init__.py", line 1, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.base_model import BaseModelAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/__init__.py", line 1, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.base_model.adapter import BaseModelAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/adapter.py", line 7, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/__init__.py", line 1, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.pydantic.adapter import PydanticAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/adapter.py", line 8, in 2026-02-13 21:27:48.073000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/base.py", line 11, in 2026-02-13 21:27:48.073000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/__init__.py", line 18, in 2026-02-13 21:27:48.073000 from key_value.shared.managed_entry import ManagedEntry 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/managed_entry.py", line 16, in 2026-02-13 21:27:48.073000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:48.073000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in 2026-02-13 21:27:48.073000 from key_value.shared.errors.wrappers import ( 2026-02-13 21:27:48.073000 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py) 2026-02-13 21:27:48.390000 RequestId: 22477042-474e-4243-b800-6cf23b1c030b Error: Runtime exited with error: exit status 1 Runtime.ExitError 2026-02-13 21:27:52.391000 Traceback (most recent call last): 2026-02-13 21:27:52.391000 File "/usr/local/bin/fastmcp", line 4, in 2026-02-13 21:27:52.391000 from fastmcp.cli import app 2026-02-13 21:27:52.391000 File "/usr/local/lib/python3.12/site-packages/fastmcp/__init__.py", line 15, in 2026-02-13 21:27:52.391000 from fastmcp.server.server import FastMCP 2026-02-13 21:27:52.391000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/__init__.py", line 1, in 2026-02-13 21:27:52.391000 from .context import Context 2026-02-13 21:27:52.391000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/context.py", line 28, in 2026-02-13 21:27:52.392000 from fastmcp.resources.resource import ResourceResult 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/__init__.py", line 1, in 2026-02-13 21:27:52.392000 from .function_resource import FunctionResource, resource 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/function_resource.py", line 17, in 2026-02-13 21:27:52.392000 from fastmcp.resources.resource import Resource, ResourceResult 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/resources/resource.py", line 32, in 2026-02-13 21:27:52.392000 from fastmcp.server.auth.authorization import AuthCheck 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/__init__.py", line 17, in 2026-02-13 21:27:52.392000 from .oauth_proxy import OAuthProxy 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/__init__.py", line 10, in 2026-02-13 21:27:52.392000 from fastmcp.server.auth.oauth_proxy.proxy import OAuthProxy 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/fastmcp/server/auth/oauth_proxy/proxy.py", line 32, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.pydantic import PydanticAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/__init__.py", line 1, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.base_model import BaseModelAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/__init__.py", line 1, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.base_model.adapter import BaseModelAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/base_model/adapter.py", line 7, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/__init__.py", line 1, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.pydantic.adapter import PydanticAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/adapter.py", line 8, in 2026-02-13 21:27:52.392000 from key_value.aio.adapters.pydantic.base import BasePydanticAdapter 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/aio/adapters/pydantic/base.py", line 11, in 2026-02-13 21:27:52.392000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:52.392000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/__init__.py", line 18, in 2026-02-13 21:27:52.393000 from key_value.shared.managed_entry import ManagedEntry 2026-02-13 21:27:52.393000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/managed_entry.py", line 16, in 2026-02-13 21:27:52.393000 from key_value.shared.errors import DeserializationError, SerializationError 2026-02-13 21:27:52.393000 File "/usr/local/lib/python3.12/site-packages/key_value/shared/errors/__init__.py", line 39, in 2026-02-13 21:27:52.393000 from key_value.shared.errors.wrappers import ( 2026-02-13 21:27:52.393000 ImportError: cannot import name 'CorruptedDataError' from 'key_value.shared.errors.wrappers' (/usr/local/lib/python3.12/site-packages/key_value/shared/errors/wrappers/__init__.py) 2026-02-13 21:27:52.733000 RequestId: 8be5f979-161e-417a-a256-a9b0767ea3b3 Error: Runtime exited with error: exit status 1 Runtime.ExitError ```Example Code
# Based on the [quick start](https://gofastmcp.com/getting-started/quickstart) and [Prefect](https://gofastmcp.com/deployment/prefect-horizon) guides
# server.py
from fastmcp import FastMCP
mcp = FastMCP("MyServer")
@mcp.tool
def hello(name: str) -> str:
return f"Hello, {name}!"Version Information
% uv pip install --upgrade fastmcp
Resolved 68 packages in 123ms
Audited 68 packages in 1ms
% uv run fastmcp version
FastMCP version: 3.0.0rc1
MCP version: 1.26.0
Python version: 3.12.12
Platform: macOS-26.3-arm64-arm-64bit
FastMCP root path: /Users/.../mango-test-mcp/.venv/lib/python3.12/site-packages
% uv run fastmcp inspect server.py:mcp
Server
Name: My MCP Server
Version: 3.0.0rc1
Generation: 2
Components
Tools: 1
Prompts: 0
Resources: 0
Templates: 0
Environment
FastMCP: 3.0.0rc1
MCP: 1.26.0
% uv run fastmcp inspect -f fastmcp -o output.json "server.py:mcp"
[02/13/26 13:29:21] INFO Server inspection complete. Report saved to output.json cli.py:833
✓ Server inspection saved to: output.json
Server: MyServer
Format: fastmcp
{
"server": {
"name": "MyServer",
"instructions": null,
"version": "3.0.0rc1",
"website_url": null,
"icons": null,
"generation": 2,
"capabilities": {
"tools": {
"listChanged": true
},
"resources": {
"subscribe": false,
"listChanged": false
},
"prompts": {
"listChanged": false
},
"logging": {}
}
},
"environment": {
"fastmcp": "3.0.0rc1",
"mcp": "1.26.0"
},
"tools": [
{
"key": "tool:hello@",
"name": "hello",
"description": null,
"input_schema": {
"additionalProperties": false,
"properties": {
"name": {
"type": "string"
}
},
"required": [
"name"
],
"type": "object"
},
"output_schema": {
"properties": {
"result": {
"type": "string"
}
},
"required": [
"result"
],
"type": "object",
"x-fastmcp-wrap-result": true
},
"annotations": null,
"tags": null,
"title": null,
"icons": null,
"meta": null
}
],
"prompts": [],
"resources": [],
"templates": []
}