Lifecycle Test Initialize Then Tools

Prove the handshake before the tool list, because a client never calls tools on a failed initialize

Use when: a new server is being validated against a real client for the first time

Avoid when: the transport is already proven and only a single tool changed

Procedure

1. Send initialize with a supported protocolVersion and client info
2. Assert protocolVersion, capabilities and serverInfo in the reply
3. Send the initialized notification and expect no reply
4. Send tools/list and assert every tool has a name, description and schema
5. Call one tool and assert the result shape
6. Record the whole sequence as a transcript fixture

Signals

• initialize returns before any tool call is attempted
• the initialized notification produces no response line
• tools/list returns a non-empty array with schemas
• the first tool call succeeds on the same connection

Patterns

1. Handshake

initialize -> initialized -> tools/list -> tools/call

2. No reply

notifications never produce a response id

3. Schema check

each tool has inputSchema.type == 'object'

Pitfalls

• Skipping the notification and wondering why a strict client stalls
• Calling a tool before initialize completes
• Asserting the tool list without checking schema presence

Done when

• the full sequence passes on one connection in one process
• the transcript fixture is committed

References

• MCP - lifecycle
• MCP - tools