AI agents use putString to create or update resources in Tencent Cloud COS MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Tencent Cloud COS MCP Server environment.
This tool creates or uploads content to a cloud storage bucket (Tencent COS), which is a reversible write operation. While it modifies cloud storage state, the data can be updated or deleted later, distinguishing it from Destructive operations.
From the tool's definition Tool name 'putString' and description '上传字符串内容到存储桶' (upload string content to storage bucket) indicate creation/modification of data in cloud storage without irreversible deletion.
Documented attack patterns abuse exactly the kind of access putString gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tencent Cloud COS MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for putString:
{
"version": "1",
"default": "deny",
"tools": {
"putString": {
"limits": [
{
"counter": "putstring_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}putString 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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上传字符串内容到存储桶. It is categorised as a Write tool in the Tencent Cloud COS MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Tencent Cloud COS MCP Server MCP server in PolicyLayer and add a rule for putString: 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 Tencent Cloud COS MCP Server. Nothing to install.
putString 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 putString 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 putString. 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.
putString is provided by the Tencent Cloud COS MCP Server MCP server (tencent/cos-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 21 Tencent Cloud COS MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
21 Tencent Cloud COS MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.