epost · Entrez MCP Server MCP: Risk & Policy

WHAT IT DOES

What epost does on Entrez MCP Server

AI agents use epost to create or update resources in Entrez MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Entrez MCP Server environment.

WHY IT NEEDS A POLICY

Why epost needs a policy

The epost tool creates temporary records on NCBI's Entrez History server by uploading UIDs (unique identifiers). This is a write operation that stores data (query_key and WebEnv session identifiers) for downstream processing. However, it is reversible and non-destructive—the uploaded data is temporary session state used for batch workflow optimization, not permanent modifications to biomedical records.

From the tool's definition Tool description states 'Upload UIDs to the Entrez History server' and 'returns query_key and WebEnv for pipeline workflows.' The term 'upload' indicates data is being written to a server-side history cache.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

epost Rate-limited

epost 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "epost": {
      "limits": [
        {
          "counter": "epost_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Entrez MCP Server, so you can run agents against it safely.

FAQ

Questions about epost

What does the epost tool do? +

Upload UIDs to the Entrez History server for efficient batch processing. Essential for large datasets - upload thousands of IDs once, then use with other E-utilities. Returns query_key and WebEnv for pipeline workflows. It is categorised as a Write tool in the Entrez MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on epost? +

Register the Entrez MCP Server MCP server in PolicyLayer and add a rule for epost: 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 Entrez MCP Server. Nothing to install.

What risk level is epost? +

epost is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit epost? +

Yes. Add a rate_limit block to the epost 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.

How do I block epost completely? +

Set action: deny in the PolicyLayer policy for epost. 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.

What MCP server provides epost? +

epost is provided by the Entrez MCP Server MCP server (leongxj123/entrez-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.