firecrawl_research_search_papers returns 404 when using self-hosted Firecrawl

I'm using a self-hosted Firecrawl service, and most MCP search tools are working as expected. However, the firecrawl_research_search_papers tool consistently fails.

**The error I receive is:**

Tool 'firecrawl_research_search_papers' execution failed:

Request failed with status code 404

**Environment**

Firecrawl: Self-hosted
MCP Server :
```
command: "npx"
args:
- "-y"
- "firecrawl-mcp"
```

**Expected Behavior**

The firecrawl_research_search_papers tool should execute successfully and return research paper search results.

using a

Start at the implementation of the firecrawl_research_search_papers MCP tool and trace the request it sends for self-hosted Firecrawl, then compare it with the working search tools described in the report. Confirm the fix by exercising the tool against a self-hosted service and verifying that research paper results are returned without a 404.

Written by the indexing model from the issue text.