Merge data into a specific record. Only updates specified fields.
AI agents use merge to create or update resources in SurrealDB MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your SurrealDB MCP Server environment.
A merge operation that updates fields in a record is a classic Write operation. It modifies existing data but is reversible through further updates. It does not execute arbitrary code (Execute), delete data (Destructive), move money (Financial), or merely retrieve data (Read). Given the presence of sibling destructive tools like 'delete' on this server, 'merge' clearly falls into the Write category.
From the tool's definition The tool 'merge' is described as updating specified fields in a record, which is a reversible modification of data. This aligns with Write category tools that 'create or modify data reversibly' (update, post, upload).
Documented attack patterns abuse exactly the kind of access merge gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and SurrealDB MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for merge:
{
"version": "1",
"default": "deny",
"tools": {
"merge": {
"limits": [
{
"counter": "merge_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}merge stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Merge data into a specific record. Only updates specified fields. It is categorised as a Write tool in the SurrealDB MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the SurrealDB MCP Server MCP server in PolicyLayer and add a rule for merge: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches SurrealDB MCP Server. Nothing to install.
merge is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the merge rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for merge. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
merge is provided by the SurrealDB MCP Server MCP server (nsxdavid/surrealdb-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 10 SurrealDB MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
10 SurrealDB MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.