Using attach_mcp

How to make an MCP server usable by an agent (the link create_mcp does not make).

Slug: tool-attach-mcp Agent-internal: loaded on demand via skill_view (hidden from the dashboard library, not user-assigned).

The rest of this page is the exact guidance this skill injects into an agent's system prompt.

Using attach_mcp

Creating an MCP server is NOT enough — its tools reach an agent only once the MCP is attached to that agent. attach_mcp creates that link.

Fields

• mcpSlug: the existing MCP server (e.g. "cogni-cortex").
• agentSlug: the agent that should get the MCP's tools.

When to use

• After create_mcp when you did NOT pass attachToAgentSlug.
• To give an existing MCP to an additional agent.

The usual flow (one agent gets a new MCP)

Prefer doing it in one call: create_mcp with attachToAgentSlug: "<agent>". Use attach_mcp when the server already exists or you want a second agent to have it.

Worked example

{ "mcpSlug": "cogni-cortex", "agentSlug": "my-agent" }

After this, the agent's next run can call the MCP's <slug>__* tools. Without it, the agent will report "I don't have that tool".

Common mistakes

• ❌ create_mcp then delegate, expecting the tools to be there → ✅ attach first (or use attachToAgentSlug).
• ❌ attaching to the orchestrator when a sub-agent needs the tools → attach to the agent that will actually use them.