Similarity search by SMILES
AI agents call search_similarity to retrieve information from Chemspace MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only search operation against the Chemspace chemical database. It takes a SMILES string as input and returns matching compounds based on similarity. There are no side effects, no data modification, no code execution, and no destructive or financial operations involved. It is purely a retrieval/query function.
From the tool's definition Tool name 'search_similarity' and description 'Similarity search by SMILES' indicate a query operation that retrieves data from the Chemspace API without modifying or executing operations.
Attacks that exploit this kind of access
Similarity search by SMILES. It is categorised as a Read tool in the Chemspace MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Chemspace MCP Server MCP server in PolicyLayer and add a rule for search_similarity: 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 Chemspace MCP Server. Nothing to install.
search_similarity 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 search_similarity 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 search_similarity. 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.
search_similarity is provided by the Chemspace MCP Server MCP server (lukasmki/chemspace-mcp). 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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