Add SupportsWebFetch property to agentic engines and automatic web-fetch server integration

[Copilot]

Add SupportsWebFetch property to agentic engines

✅ Completed tasks:

• Add SupportsWebFetch() method to CodingAgentEngine interface in agentic_engine.go
• Add supportsWebFetch field to BaseEngine struct
• Implement SupportsWebFetch() method in BaseEngine
• Set supportsWebFetch to appropriate values for each engine (Claude=true, Codex/Copilot/Custom=false)
• Create pkg/workflow/fetch.go with shared code to add web-fetch MCP server
• Update compiler to check SupportsWebFetch() and add MCP fetch server when needed
• Update all engines (Claude, Codex, Copilot, Custom) to render web-fetch server configuration
• Write unit tests for the new functionality
• Write integration tests to verify end-to-end behavior
• Build and test all changes - all tests pass ✓
• Manually verify the behavior with test workflows
• Address code review comments about config usage
• Change MCP server name from "mcp/fetch" to "web-fetch" per review feedback
• Use mcp/fetch Docker image from Docker Hub
• Update dev.md to test web-fetch functionality
• Add "tools": ["*"] field for Copilot engine MCP configurations
• Add --allow-tool web-fetch permission for Copilot engine

Implementation details:

• Claude engine supports web-fetch natively (supportsWebFetch=true) - uses native WebFetch tool
• Codex, Copilot, and Custom engines don't support web-fetch natively (supportsWebFetch=false)
• When web-fetch tool is requested and engine doesn't support it, the compiler automatically adds web-fetch MCP server
• Shared rendering code in fetch.go supports both JSON (Claude, Custom, Copilot) and TOML (Codex) formats
• The web-fetch MCP server uses mcp/fetch Docker image from Docker Hub
• Server name is "web-fetch" to match the tool name for consistency
• Copilot engine MCP servers include "tools": ["*"] field as required by Copilot CLI
• Copilot engine now adds --allow-tool web-fetch permission when web-fetch MCP server is configured
• dev.md workflow now includes web-fetch testing

Verification:

• ✅ Copilot workflow with web-fetch → web-fetch MCP server added with "tools": ["*"] field and --allow-tool web-fetch permission
• ✅ Codex workflow with web-fetch → web-fetch MCP server added (TOML format, no tools field)
• ✅ Claude workflow with web-fetch → WebFetch native tool used (no MCP server)
• ✅ All unit tests pass (11 test cases including new tools field tests)
• ✅ All integration tests pass (3 scenarios tested)
• ✅ Code formatted correctly with make fmt
• ✅ All code review comments addressed

Original prompt

Add a property to the agentic engine, supportsWrbFetch that determines of the engine has builtin support for the web-fetch tool.

If not supported add the "mcp/fetch" dockerized mcp server to the mcp server configuration. (This code should be shared, place in fetch.go)

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[pelikhan]

@copilot the copilot agentic engine requires ' "tools": ["*"],' in the mcp server configurations.

[Copilot]

@copilot the copilot agentic engine requires ' "tools": ["*"],' in the mcp server configurations.

Added "tools": ["*"] field to Copilot web-fetch MCP server configuration in commit 4343f1d.

Copilot output:

"web-fetch": {
  "command": "docker",
  "args": ["run", "-i", "--rm", "mcp/fetch"],
  "tools": ["*"]
}

Other engines (Claude, Codex, Custom) don't include this field as they don't require it.

[pelikhan]

@copilot update the tool allow list for web-fetch to use any tools in the copilot engine.

--allow-tool web-fetch

See error in https://github.com/githubnext/gh-aw/actions/runs/18182698880/job/51761513740

[Copilot]

@copilot update the tool allow list for web-fetch to use any tools in the copilot engine.

--allow-tool web-fetch...

Added --allow-tool web-fetch permission for Copilot engine in commit 549f961.

Change: Removed web-fetch from builtInTools list so it's processed as an MCP server and gets the allow-tool permission.

Copilot command output:

copilot ... --allow-tool safe_outputs --allow-tool web-fetch --prompt "$INSTRUCTION"

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/githubnext/gh-aw/actions/runs/18182698880/jobs
  • Triggering command: curl -s REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)