Devin Desktop 100-tool limit: fit Sume's MCP tools with disabledTools

Cascade, the agent in Devin Desktop (the app formerly called Windsurf), can use at most 100 tools at any given time, counted across every connected MCP server. Sume's own tool inventory in its docs names roughly 75 tool ids, so Sume alone fits, but it leaves about 25 slots for everything else. When you hit the cap, switch individual tools off with disabledTools in mcp_config.json instead of removing whole servers.

The limit and the config fields come from Devin's page Cascade MCP integration, read on 2026-10-02 (the old docs.windsurf.com URL redirects there). Sume's inventory is on MCP tools and gates. Counts depend on your session, so treat my number as an estimate and read the live one from tools_list.

What exactly is the limit?

Devin's page says Cascade has a limit of 100 total tools that it has access to at any given time. The config file is ~/.config/devin/mcp_config.json on macOS and Linux, and %APPDATA%\devin\mcp_config.json on Windows. A remote HTTP server uses serverUrl (or url) plus an optional headers object. The page does not say what Cascade does with tool number 101, so do not rely on a particular failure mode; stay under the cap.

How many tools does Sume add?

Sume's tools-and-gates page groups the hosted registry: meta and health tools, account and catalog, jobs, assets, image, video and audio generation, avatars, crawl, and media inspect, import and timeline tools. Counting the names in that inventory gives about 75, not counting a few dest-only or retired entries. The session you get may show fewer.

OAuth with mcp:read only shows read-only tools, so a person who left Write off sees a smaller list than an API-key session, which sees the full hosted set. Call tools_list and count; mcp_health also reports the endpoint's readiness and auth source. Sume's tools_list is the source of truth, not any blog number.

How do I trim tools without losing Sume?

Devin's page says individual tools are disabled through a disabledTools array in mcp_config.json, listing tool names to block. Put the names you do not use there. A video-only workflow can drop the Avatar and crawl tools; a research workflow can drop the paid generation tools, which also keeps them out of reach. Sume's tool ids are underscore names such as avatars_create and crawl_scrape.

Use this as a starting point, then check the exact key placement against Devin's page, since the page summary I read names the array but you should confirm its position in the server entry.

{
  "mcpServers": {
    "sume": {
      "serverUrl": "https://mcp.sume.com/mcp",
      "headers": { "x-api-key": "${env:SUME_API_KEY}" },
      "disabledTools": ["avatars_create", "crawl_site"]
    }
  }
}

Why trimming also helps cost and safety

A smaller list keeps paid tools away from an agent that has no reason to call them. It does not replace Sume's own gates: every paid call needs an idempotency_key, dry_run=true previews the cost, and max_spend_usd caps a call when you pass it. If you would rather keep the list short at the source, use an OAuth session with Write off, which hides mutating and paid tools completely.

Which Sume tools can I drop first?

Drop by job, not by guesswork. Sume's docs group tools by family, so you can switch off a whole family that your workflow never touches. Keep the discovery and job tools in every case: tools_list, tools_schema, mcp_health, jobs_status, jobs_wait and jobs_result, because every generation ends in a job you have to read.

How do I verify the count in Devin Desktop?

Add Sume first with no other servers, call tools_list, and count the entries. Then add your other servers one at a time and watch the total against 100. If an agent says it cannot find a tool you know exists, suspect the cap before the connection: ask it to call mcp_health, and if that works the connection is fine. For one tool's contract without loading everything into the prompt, tools_schema with a name returns that single tool's definition.

What does this not fix?

Disabling a tool in Devin Desktop does not change Sume's account, and it does not change what an API key can do on Sume's side. A key still reaches the full tool set from any other client. If the limit is the problem, there is no Sume setting that shrinks the registry; the control is on the client.