Reduce context usage for list_releases

[kerobbi]

Summary

Reduces context usage for list_releases by adding a convertToMinimalRelease function for the existing MinimalRelease type.

Field preserved

id, tag_name, name, body, html_url, published_at, prerelease, draft, author (MinimalUser)

Fields dropped

node_id, url, assets_url, upload_url, zipball_url, tarball_url, target_commitish, created_at, assets (full array with nested objects), immutable, full User object (-> MinimalUser)

Single Item Payload Diff

Before

	{
		"tag_name": "v19.2.4",
		"target_commitish": "main",
		"name": "19.2.4 (January 26th, 2026)",
		"body": "## React Server Components\r\n\r\n- Add more DoS mitigations to Server Actions, and harden Server Components ([#35632](https://github.com/facebook/react/pull/35632) by @gnoff, @lubieowoce, @sebmarkbage, @unstubbable)",
		"draft": false,
		"prerelease": false,
		"id": 279999398,
		"created_at": "2026-01-26T17:04:55Z",
		"published_at": "2026-01-26T18:29:43Z",
		"url": "https://api.github.com/repos/facebook/react/releases/279999398",
		"html_url": "https://github.com/facebook/react/releases/tag/v19.2.4",
		"assets_url": "https://api.github.com/repos/facebook/react/releases/279999398/assets",
		"upload_url": "https://uploads.github.com/repos/facebook/react/releases/279999398/assets{?name,label}",
		"zipball_url": "https://api.github.com/repos/facebook/react/zipball/v19.2.4",
		"tarball_url": "https://api.github.com/repos/facebook/react/tarball/v19.2.4",
		"author": {
			"login": "eps1lon",
			"id": 12292047,
			"node_id": "MDQ6VXNlcjEyMjkyMDQ3",
			"avatar_url": "https://avatars.githubusercontent.com/u/12292047?v=4",
			"html_url": "https://github.com/eps1lon",
			"gravatar_id": "",
			"type": "User",
			"site_admin": false,
			"url": "https://api.github.com/users/eps1lon",
			"events_url": "https://api.github.com/users/eps1lon/events{/privacy}",
			"following_url": "https://api.github.com/users/eps1lon/following{/other_user}",
			"followers_url": "https://api.github.com/users/eps1lon/followers",
			"gists_url": "https://api.github.com/users/eps1lon/gists{/gist_id}",
			"organizations_url": "https://api.github.com/users/eps1lon/orgs",
			"received_events_url": "https://api.github.com/users/eps1lon/received_events",
			"repos_url": "https://api.github.com/users/eps1lon/repos",
			"starred_url": "https://api.github.com/users/eps1lon/starred{/owner}{/repo}",
			"subscriptions_url": "https://api.github.com/users/eps1lon/subscriptions"
		},
		"node_id": "RE_kwDOAJy2Ks4QsHOm",
		"immutable": false
	}

After

	{
		"id": 279999398,
		"tag_name": "v19.2.4",
		"name": "19.2.4 (January 26th, 2026)",
		"body": "## React Server Components\r\n\r\n- Add more DoS mitigations to Server Actions, and harden Server Components ([#35632](https://github.com/facebook/react/pull/35632) by @gnoff, @lubieowoce, @sebmarkbage, @unstubbable)",
		"html_url": "https://github.com/facebook/react/releases/tag/v19.2.4",
		"published_at": "2026-01-26T18:29:43Z",
		"prerelease": false,
		"draft": false,
		"author": {
			"login": "eps1lon",
			"id": 12292047,
			"profile_url": "https://github.com/eps1lon",
			"avatar_url": "https://avatars.githubusercontent.com/u/12292047?v=4"
		}
	}

Token Reduction

Measured using a script that makes use of OAI's tiktoken library (o200k_base) at 2 and 25 items.

Items	Baseline	Optimised	Reduction
2	1,348	480	64.4%
25	44,912	33,996	24.3%

Why

list_releases was returning raw *github.RepositoryRelease objects with ~20+ fields including nested assets arrays, API URLs, and full user objects. Most of this is noise not useful for model reasoning. Details are available via get_latest_release or get_release_by_tag.

What changed

• Added convertToMinimalRelease conversion function
• Wired convertToMinimalRelease in list_releases
• Updated relevant tests

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Prompts tested (tool changes only)

• List the last 2 releases in facebook/react
• List the last 25 releases in facebook/react

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test

Docs

• Not needed
• Updated (README / docs / examples)

[Copilot]

Pull request overview

This PR reduces context/token usage for the list_releases MCP tool by returning a trimmed MinimalRelease representation instead of the full *github.RepositoryRelease payload.

Changes:

• Added convertToMinimalRelease(*github.RepositoryRelease) MinimalRelease for consistent minimal release serialization.
• Updated list_releases to convert each release to MinimalRelease before marshalling.
• Adjusted Test_ListReleases to unmarshal and validate the minimalized response type.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
pkg/github/repositories.go	Convert ListReleases output to []MinimalRelease before JSON marshalling.
pkg/github/minimal_types.go	Add convertToMinimalRelease helper that populates the existing MinimalRelease type (including RFC3339 published_at).
pkg/github/repositories_test.go	Update Test_ListReleases to unmarshal into []MinimalRelease and validate tag_name values.