Claude Code subagent MCP server: scope Sume tools to one

Yes: a Claude Code subagent can have its own MCP server. List it under mcpServers in the subagent's frontmatter, either as the name of a server you already configured or as an inline definition that only that subagent sees. An inline server connects when the subagent starts and disconnects when it finishes, and the main conversation never loads its tool descriptions.

That is from Anthropic's subagents page, read 2026-09-29. Sume's hosted MCP endpoint is https://mcp.sume.com/mcp, per the MCP quickstart. Below are both routes for a subagent that makes video and image clips.

How do I define an inline Sume server for one subagent?

Save this as .claude/agents/clip-maker.md. The sume key is the server name; the entry uses the same schema as a .mcp.json server, and http is one of the supported types. The header authenticates with an API key from an environment variable, which keeps the key out of the file.

---
name: clip-maker
description: Makes short video and image clips with Sume. Use for any clip request.
mcpServers:
  - sume:
      type: http
      url: https://mcp.sume.com/mcp
      headers:
        Authorization: Bearer ${SUME_API_KEY}
---
Use the Sume tools. Preview a paid call with dry_run first,
send max_spend_usd, and wait with jobs_wait on the job id.

How do I reuse a server I already added?

If you ran claude mcp add --transport http sume https://mcp.sume.com/mcp and signed in, reference it by name. A string reference shares the parent session's connection. Add a tools allowlist to narrow the subagent to a few tools. Anthropic's page says tools and disallowedTools accept mcp__<server> and mcp__<server>__* patterns.

---
name: clip-maker
description: Makes short video clips with Sume.
tools: Read, mcp__sume__generate_video, mcp__sume__jobs_wait, mcp__sume__jobs_result
mcpServers:
  - sume
---

What can and can't a subagent do with MCP?

Anthropic's page answers these questions about subagents and MCP tools.

Can the subagent wait for a video job?

Yes, but one jobs_wait call holds at most 55 seconds (default 50). Sume's jobs docs say to repeat the wait with the same ids when it returns wait_slice_expired, never to resubmit the paid create. Put that rule in the subagent's prompt. jobs_wait also takes up to 20 ids in job_ids, so one wait can cover a batch.

Paid tools such as generate_video need an idempotency_key, and dry_run and max_spend_usd are optional gates, per Sume's MCP tools and gates. A subagent does not add its own spend limit, so tell it to send the cap.

Why did my subagent file not load the server?

Anthropic's page says field names are camelCase and must match the table exactly, and that Claude Code ignores a field it does not recognize without reporting an error. A misspelled mcpServers gives you a subagent with no Sume tools and no warning.

An untrusted project folder also skips inline servers until you accept the trust dialog, and managed MCP restrictions such as allowedMcpServers and deniedMcpServers cover subagent servers too. For sharing one server across a team instead, see Claude Code MCP project scope.