Add Repository Tree Navigation Tool #1164
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Pull Request Overview
This PR adds a new get_repository_tree tool to the GitHub MCP Server, enabling AI assistants to explore and understand repository file structures through natural language interfaces. This addresses the navigation capability gap between VS Code agent mode and dotcom chat.
- Adds
GetRepositoryTreefunction with support for recursive exploration and path filtering - Implements comprehensive test coverage for the new tool functionality
- Updates tool registration and documentation to include the new capability
Reviewed Changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| pkg/github/tools.go | Registers the new GetRepositoryTree tool in the repos toolset |
| pkg/github/repositories.go | Implements the GetRepositoryTree function with GitHub Git Tree API integration |
| pkg/github/repositories_test.go | Adds comprehensive test cases for the new tool including error scenarios |
| pkg/github/toolsnaps/get_repository_tree.snap | Tool definition snapshot for testing |
| README.md | Documents the new tool parameters and usage |
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| response := TreeResponse{ | ||
| SHA: *tree.SHA, | ||
| Truncated: *tree.Truncated, |
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Potential nil pointer dereference when dereferencing tree.SHA and tree.Truncated from the GitHub API response without null checks.
| response := TreeResponse{ | |
| SHA: *tree.SHA, | |
| Truncated: *tree.Truncated, | |
| var sha string | |
| if tree.SHA != nil { | |
| sha = *tree.SHA | |
| } else { | |
| sha = "" | |
| } | |
| var truncated bool | |
| if tree.Truncated != nil { | |
| truncated = *tree.Truncated | |
| } else { | |
| truncated = false | |
| } | |
| response := TreeResponse{ | |
| SHA: sha, | |
| Truncated: truncated, |
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| } | ||
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| // Get the tree using the GitHub Git Tree API | ||
| tree, resp, err := client.Git.GetTree(ctx, owner, repo, treeSHA, recursive) |
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Does the client handle recursive: false such that it won't return recursive entries? The docs suggest that we'll need to omit the recursive parameter completely in order to prevent recursion:
Setting this parameter to any value returns the objects or subtrees referenced by the tree specified in :tree_sha. For example, setting recursive to any of the following will enable returning objects or subtrees: 0, 1, "true", and "false". Omit this parameter to prevent recursively returning objects or subtrees.
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Ah, yep, it looks like the client will only include the recursive parameter if it's true: https://github.com/google/go-github/blob/46f1bf23e6f9659d04f9eaebff5d25902cddfd8e/github/git_trees.go#L102-L104
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| response := TreeResponse{ | ||
| SHA: *tree.SHA, | ||
| Truncated: *tree.Truncated, | ||
| Tree: treeEntries, | ||
| TreeSHA: treeSHA, | ||
| Owner: owner, | ||
| Repo: repo, | ||
| Recursive: recursive, | ||
| Count: len(filteredEntries), | ||
| } | ||
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| r, err := json.Marshal(response) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to marshal response: %w", err) | ||
| } | ||
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| return mcp.NewToolResultText(string(r)), nil |
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We have support for Output Schemas now, so you could move TreeResponse and TreeResponseEntry struct type definitions out of this func, and make it a structured output for the tool, rather than passing back escaped JSON e.g. https://github.com/mark3labs/mcp-go/blob/main/examples/structured_input_and_output/README.md.
Closes: https://github.com/github/copilot-agent-services/issues/651
This PR adds a new
get_repository_treetool to the GitHub MCP Server, enabling natural language exploration of repository file structures.What's Added
New Tool:
get_repository_tree- Retrieves repository file/directory structure using GitHub's Git Tree APIResponse Types: TreeResponse and TreeEntryResponse structs for structured data
Tool Registration: Added to the "repos" toolset alongside existing repository tools
Recursive Exploration: Optional recursive directory traversal
Path Filtering: Filter results by directory prefix (e.g., src/, pkg)
Branch/SHA Support: Query specific branches, tags, or commit SHAs
Rich Metadata: Returns file types, modes, SHAs, and URLs
Impact
This addresses the navigation capability gap between VS Code agent mode (which has CLI access for ls) and dotcom chat, enabling AI assistants to naturally explore and understand repository structures through conversational interfaces.
I was able to use this tool in VS code:
