Tool not available
Tool availability has two halves, and both are required:
- The tool set is registered by the server.
- The tool set is listed on the agent in
tools.
Listing a name the server does not provide does not grant it. This is deliberate - it means an agent cannot pick up a new capability just because someone deployed a tool.
code_agent appears conditionally. It is supplied through the local or remote sandbox tool
set, and only shows up when its coding-agent credential and safety settings permit. See
Use built-in tools.
MCP tools are namespaced. They arrive as mcp__<server>__<tool>, not under their bare name.
If the server itself is not connecting, check the transport and credentials in mcp.toml. MCP
servers connect at startup. When some servers connected and one did not, the failed one is
named in the agent's own system prompt - the agent will say the server is unavailable rather
than improvising with other tools. When every server failed, MCP is disabled for that agent
entirely (the tools are simply absent). Either way: fix the server and restart to reconnect.
Next
- Use built-in tools - what ships with the server.
- Connect an MCP server - external tools and their naming.