Add an EIP-712 cryptographic signature to a CID for content verification
AI agents use addSignature to create or update resources in Pinata MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Pinata MCP environment.
This tool writes/attaches a cryptographic signature to a CID (Content Identifier). It creates new data (a signature record) associated with existing content, which is a reversible write operation. It does not delete data, execute code, or involve financial transactions. Misuse could associate fraudulent or misleading signatures with content, hence medium severity.
From the tool's definition Add an EIP-712 cryptographic signature to a CID for content verification
Documented attack patterns abuse exactly the kind of access addSignature gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Pinata MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for addSignature:
{
"version": "1",
"default": "deny",
"tools": {
"addSignature": {
"limits": [
{
"counter": "addsignature_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}addSignature 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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Add an EIP-712 cryptographic signature to a CID for content verification. It is categorised as a Write tool in the Pinata MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Pinata MCP server in PolicyLayer and add a rule for addSignature: 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 Pinata MCP. Nothing to install.
addSignature 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 addSignature 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 addSignature. 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.
addSignature is provided by the Pinata MCP server (pinatacloud/pinata-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Pinata MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
35 Pinata MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.