List all stored credentials with essential data (id, app name, and username only if multiple apps)
AI agents call list_credentials to retrieve information from Credential Manager 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 credential metadata but does not create, modify, delete, or execute operations. However, severity is elevated to 'high' because listing credentials (even partial data like app names and usernames) exposes sensitive authentication metadata.
From the tool's definition Tool name 'list_credentials' and description 'List all stored credentials' indicates data retrieval with no modification. The description explicitly limits output to 'id, app name, and username only if multiple apps', confirming a read-only operation.
Attacks that exploit this kind of access
List all stored credentials with essential data (id, app name, and username only if multiple apps). It is categorised as a Read tool in the Credential Manager MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Credential Manager MCP Server MCP server in PolicyLayer and add a rule for list_credentials: 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 Credential Manager MCP Server. Nothing to install.
list_credentials 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 list_credentials 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 list_credentials. 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.
list_credentials is provided by the Credential Manager MCP Server MCP server (mclamee/credential-manager-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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