Update docs to include tool renaming guide (#1623)

* update docs

* Update docs/tool-renaming.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

CONTRIBUTING.md

@@ -39,6 +39,7 @@ These are one time installations required to be able to test your changes locall
     - Run linter: `script/lint`
     - Update snapshots and run tests: `UPDATE_TOOLSNAPS=true go test ./...`
     - Update readme documentation: `script/generate-docs`
+    - If renaming a tool, add a deprecation alias (see [Tool Renaming Guide](docs/tool-renaming.md))
 6. Push to your fork and [submit a pull request][pr] targeting the `main` branch
 7. Pat yourself on the back and wait for your pull request to be reviewed and merged.
 

docs/tool-renaming.md

@@ -0,0 +1,42 @@
+# Tool Renaming Guide
+
+How to safely rename MCP tools without breaking existing user configurations.
+
+## Overview
+
+When tools are renamed, users who have the old tool name in their MCP configuration (for example, in `X-MCP-Tools` headers for the remote MCP server or `--tools` flags for the local MCP server) would normally get errors. 
+The deprecation alias system allows us to maintain backward compatibility by silently resolving old tool names to their new canonical names.
+
+This allows us to rename tools safely, without introducing breaking changes for users that have a hard reference to those tools in their server configuration.
+
+## Quick Steps
+
+1. **Rename the tool** in your code (as usual, this will imply a range of changes like updating the tool registration, the tests and the toolsnaps).
+2. **Add a deprecation alias** in [pkg/github/deprecated_tool_aliases.go](../pkg/github/deprecated_tool_aliases.go):
+   ```go
+   var DeprecatedToolAliases = map[string]string{
+       "old_tool_name": "new_tool_name",
+   }
+   ```
+3. **Update documentation** (README, etc.) to reference the new canonical name
+
+That's it. The server will silently resolve old names to new ones. This will work across both local and remote MCP servers.
+
+## Example
+
+If renaming `get_issue` to `issue_read`:
+
+```go
+var DeprecatedToolAliases = map[string]string{
+    "get_issue": "issue_read",
+}
+```
+
+A user with this configuration:
+```json
+{
+  "--tools": "get_issue,get_file_contents"
+}
+```
+
+Will get `issue_read` and `get_file_contents` tools registered, with no errors.