System Prompt
memvault tools include descriptions that guide models to use them correctly. However, adding an explicit instruction to your system prompt produces the most reliable behavior — some models may skip memvault_recall without it.
Recommended
Always call memvault_recall at the start of each conversation before responding.
Save anything the user tells you about their preferences or context with memvault_remember.Why this matters
Without the instruction, recall behavior differs by model:
| Model | Recalls without instruction |
|---|---|
| claude-sonnet-4-6 | ✅ Yes (follows tool description) |
| gpt-5.4 | ⚠️ Sometimes |
The tool description already says:
"Call this at the START of every conversation before responding — even if the user hasn't asked."
But a system prompt instruction is more reliable across all models and versions.
Full example
typescript
await anthropic.messages.create({
model: "claude-sonnet-4-6",
system: `You are a helpful assistant with persistent memory.
Always call memvault_recall at the start of each conversation before responding.
Save anything the user tells you about their preferences or context with memvault_remember.`,
tools,
messages,
})