This record as markdown: /tools/io-github-2s-io-mcp/store.blob-put.md
What store.blob-put does on Mcp
AI agents use store.blob-put to create or update resources in Mcp, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp environment.
Why store.blob-put is rated Medium
This tool creates or modifies data (uploads files) but does not irreversibly delete data, so it is Write rather than Destructive. However, severity is high because combined with the financial aspect (pay-per-call in USDC), misuse could result in substantial unintended charges if an agent triggers multiple large uploads.
From the tool's definition Tool uploads or creates a file via a 'paid call' operation. The description explicitly states 'upload a file (any bytes)' which is a write operation that creates new data in persistent storage.
Attacks that exploit this kind of access
The rule that runs store.blob-put safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For store.blob-put, this is the rule to start with:
store.blob-put 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Mcp, apply this rule, and every store.blob-put call is checked against it from then on.
Questions about store.blob-put
STORE: upload a file (any bytes) in a single paid call. It is categorised as a Write tool in the Mcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP server in PolicyLayer and add a rule for store.blob-put: 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 Mcp. Nothing to install.
store.blob-put 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 store.blob-put 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 store.blob-put. 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.
store.blob-put is provided by the MCP server (@2sio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on , and thousands of servers like it.
This server
Across the catalogue