Get substance information from PubChem including substance records, synonyms, and cross-references. Search by SID, source ID, name, or external references.
AI agents call pubchem_substance to retrieve information from Entrez MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries publicly available chemical substance data from PubChem. It performs read-only operations (search and information retrieval) without any capability to modify, delete, or execute operations. The data returned is factual chemical information. There is no side effect beyond data retrieval, making this a straightforward Read category tool with low security risk.
From the tool's definition Tool description states 'Get substance information from PubChem' and 'Search by SID, source ID, name, or external references.' The verb 'Get' and 'Search' indicate retrieval operations with no modification, deletion, or execution of external operations.
Attacks that exploit this kind of access
Get substance information from PubChem including substance records, synonyms, and cross-references. Search by SID, source ID, name, or external references. It is categorised as a Read tool in the Entrez MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Entrez MCP Server MCP server in PolicyLayer and add a rule for pubchem_substance: 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.
pubchem_substance is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the pubchem_substance 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 pubchem_substance. 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.
pubchem_substance 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.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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