MCP Connected but No Tools: What to Check
Diagnose an MCP connection with missing tools by checking discovery, schema acceptance, permissions and host exposure in order.
The essentials
- A connected MCP server is not proof that its tools were discovered, accepted or exposed to the model.
- Inspect the tool list independently of the chat interface, then compare that result with the host's logs and settings.
On this page
A connected MCP server is not proof that its tools were discovered, accepted or exposed to the model. Inspect the tool list independently of the chat interface, then compare that result with the host's logs and settings.
Locate the missing step
The useful sequence is connection, protocol compatibility, tool discovery, client validation, user or policy exposure, and tool selection. Different clients may display one broad “connected” indicator across several of these stages.
Use the official MCP Inspector with the same transport and configuration as the failing client. Use trusted server code and a test account. Do not paste credentials into an issue report.
Record the server version, client version, transport and protocol revision. A result obtained through a different endpoint or identity is not an equivalent comparison.
Compare four outcomes
| Inspector result | Host result | Next step |
|---|---|---|
| No connection | No tools | Inspect launch or transport |
| Connected, empty list | No tools | Check server registration and identity |
| Tools listed | No tools | Check schema compatibility and host policy |
| Tools listed | Visible but unused | Check model mode, descriptions and task |
An upstream discovery report describes differing behavior between clients. It supports testing each boundary; it does not establish a universal workaround.
Test one harmless tool
Reduce the server to one read-only tool in a development configuration, or use one existing harmless operation. Give it a specific name, a clear description and a minimal valid input schema.
Ask the host for the exact supported task. If manual invocation succeeds but natural-language selection does not, avoid repeatedly reinstalling the server. Investigate whether the selected model or mode supports tool use and whether the tool is enabled for that conversation.
If discovery changes after a server update, refresh the client through its documented mechanism. Cached tool definitions can make an old schema appear to be the current one.
Keep approval separate
A tool may be available but require approval before execution. That is different from missing discovery. Do not solve a visibility problem by granting broad filesystem or account access.
Use the permissions audit to identify the minimum access needed. The relevant question is which boundary refused the operation, not how to remove every boundary.
Build a useful bug report
Include the sanitized tool list, the rejected schema or error, the exact client/server versions and a minimal reproduction. State whether Inspector works with the same credentials.
Success means the intended host exposes the tool and completes the harmless test. The MCP server roundup helps choose integrations; this diagnostic checks whether one actually reaches your model.
Related troubleshooting
This guide draws on the linked documentation. Examples are illustrative unless explicitly identified as measured results.
Practical guides published by Lucivo, developed with AI assistance and references to official documentation. Examples are illustrative unless a guide explicitly documents a hands-on test. Check the linked sources for current product details.
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