Attach remote MCP servers to an agent with mcpServers, then enable and set
permissions for their tools with an mcp_toolset entry in tools.
Server names must be unique within an agent version. mcpServerName must match
an entry in mcpServers. See Tools
for enablement, resources, prompts, and permission policies.
Authentication
Do not place raw credentials in the server URL or agent configuration. Store
them in a vault, attach that vault to the agent, and
install the connection through:
The installation body includes expectedAgentVersion, an idempotencyKey, a
catalog or custom connector, and authentication. Use
authentication.type: "existing_vault" with vaultId to reuse an attached
vault, static_bearer to store a new token, or none for a public server.
When an MCP server is configured directly on an agent version, Herm resolves a
matching credential from attached vaults by normalized server URL.
Herm resolves credentials when the MCP request runs; secret values are not
written into the agent’s sandbox configuration.
Updates
Use PATCH /v1/agents/{agentId} to upsert one MCP server by name while
preserving omitted servers. Use the full-replacement
POST /v1/agents/{agentId} when removing a server from the version.
MCP tool calls appear as agent.mcp_tool_use and agent.mcp_tool_result on the
session event stream. Last modified on July 25, 2026
