Run Cypher queries against the code knowledge graph. Supports MATCH, RETURN, WHERE, ORDER BY.\nExample: MATCH (n) WHERE n.name CONTAINS
AI agents invoke corn_cypher to trigger actions in CornMCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes Cypher queries against a graph database. While the description mentions read-oriented clauses (MATCH, RETURN, WHERE, ORDER BY), it says 'Run Cypher queries' without explicitly restricting write or delete operations. Cypher supports CREATE, MERGE, SET, DELETE, and DETACH DELETE. An AI agent could potentially run destructive or modifying queries.
From the tool's definition "Run Cypher queries against the code knowledge graph" — executes arbitrary Cypher statements against a graph database
Documented attack patterns abuse exactly the kind of access corn_cypher gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and CornMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for corn_cypher:
{
"version": "1",
"default": "deny",
"tools": {
"corn_cypher": {
"limits": [
{
"counter": "corn_cypher_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}corn_cypher stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Run Cypher queries against the code knowledge graph. Supports MATCH, RETURN, WHERE, ORDER BY.\nExample: MATCH (n) WHERE n.name CONTAINS. It is categorised as a Execute tool in the CornMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Corn MCP server in PolicyLayer and add a rule for corn_cypher: 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 CornMCP. Nothing to install.
corn_cypher is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the corn_cypher 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 corn_cypher. 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.
corn_cypher is provided by the Corn MCP server (yuki-20/cornmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 18 CornMCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
18 CornMCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.