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safe-fix-mcp

一个真正的 MCP 服务器,用于在 Python 仓库中查找死代码,并针对唯一一类可以安全自动移除的发现提出 分支 + PR 建议:单名称导入行上的未使用导入。它发现的其余内容——未使用的函数、类、未使用的依赖——仅保留在报告中。合并始终由人工完成。此工具本身从不合并任何内容。

为什么存在

大多数“死代码”工具都止步于报告。那些更进一步的工具通常会在没有安全网的情况下直接删除。这个工具两者都不做:它会起草一个真实、最小、可审查的 PR,并以目标仓库自身的完整测试套件在移除后确实通过为门槛——不是启发式判断,而是真正的 pytest 运行。如果测试套件失败,则不会提交或推送任何内容;仓库会保持原样。

Related MCP server: Python Code Guardian MCP Server

工具

scan_dead_code(repo_path=".", min_confidence=60)

只读。运行 vulture(死代码)和 deptry(依赖问题),并返回人类可读的发现列表。不会修改任何内容。

propose_removal_pr(repo_path=".")

  • 如果工作树不干净则拒绝执行——绝不在未提交的工作之上进行编辑。

  • 仅筛选出 vulture 置信度 ≥90% 且位于单名称导入行上的未使用导入(from x import y, z 会被跳过——删除整行会连 z 一起静默移除)。

  • 创建一个真实的分支,移除符合条件的导入,运行仓库真实的完整测试套件。

  • 仅在真正通过时:提交、推送,并尝试通过 gh pr create 打开 PR。

  • 如果 gh 未安装或未认证,分支仍然会被真实提交并推送——只有 PR 创建会降级,并返回真实错误,以便你手动打开 PR。

安装

pip install -e .

添加到你的 MCP 客户端配置中(例如 Claude Code):

claude mcp add safe-fix-mcp -- safe-fix-mcp

或者直接运行以进行本地测试:

python -m safe_fix_mcp.server

要求

  • Python ≥ 3.10

  • git 已加入 PATH

  • gh(GitHub CLI)已加入 PATH 并完成认证,如果你希望 propose_removal_pr 真正打开 PR——如果没有,分支仍然会被真实推送,工具会告诉你手动打开 PR。

开发

pip install -e ".[dev]"
pytest

已知限制

vulture 会将 scan_dead_code/propose_removal_pr 本身标记为“未使用”——这是一个已知的误报类别,而不是真正的 bug:它们由 @mcp.tool() 装饰器在运行时调度,在源码中没有被直接调用,因此静态调用图分析无法看到真正的调用者(即 MCP 框架本身)。

真实验证

scripts/verify_real_client.py 会将打包后的服务器作为真实子进程启动,并使用真实的 mcp.client.ClientSession 与之通信——这与真实 MCP 客户端使用的路径相同。在任何更改后作为冒烟测试非常有用:

python scripts/verify_real_client.py

Available Tools

2 tools
propose_removal_prA

Propose a real branch+PR removing only unused imports (single-name import lines, >= 90% vulture confidence) from a Python repository. Runs the repo's own full test suite as a safety gate before ever committing or pushing — a failure there reverts everything and nothing is committed or pushed. If gh isn't available or PR creation otherwise fails, the branch is still committed and pushed for real; only the PR itself needs opening manually. A human always merges — this never merges anything itself.

repo_path: path to a real git repository with a clean working tree (uncommitted changes are refused, not overwritten).

ParametersJSON Schema
NameRequiredDescriptionDefault
repo_pathNo.

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.5/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description fully carries the behavioral burden, and it does so well. It explains that the test suite is a safety gate, that failures revert all changes, that branch commits/pushes persist if only PR creation fails, and that human merge is always required.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is somewhat long but every sentence earns its place, covering prerequisites, side effects, failure modes, and parameter meaning. The critical safety guarantees are front-loaded, and there is no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with one optional parameter and an output schema, the description is remarkably complete. It covers prerequisites, refused inputs, failure behavior, push semantics, and merge policy, so an agent has enough to call it correctly without additional context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, but the description compensates by explaining repo_path as a real git repository with a clean working tree and noting uncommitted changes are refused. This adds meaningful semantics beyond the bare schema field, though it does not mention optionality/default behavior beyond what the schema already shows.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's specific action: propose a real branch and PR that removes unused imports from a Python repository. It adds precise scoping (single-name import lines, >=90% vulture confidence) that makes its purpose concrete and distinct from a general cleanup tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage context by specifying criteria for eligible imports and requiring a clean git repository with a full test suite. However, it never explicitly addresses when to use this tool versus scan_dead_code or mentions exclusions, leaving the routing partially to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

scan_dead_codeA

Scan a Python repository for real dead code (vulture) and dependency issues (deptry). Read-only — never modifies anything. Returns a human-readable list of findings, or "No real candidates found."

repo_path: path to the repository to scan (must contain a pyproject.toml for the dependency checks to run; dead-code scanning works regardless). min_confidence: vulture's own confidence threshold (0-100). Lower values surface more candidates but more false positives.

ParametersJSON Schema
NameRequiredDescriptionDefault
repo_pathNo.
min_confidenceNo

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.6/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations present, the description carries full burden and does so well: it states the tool is read-only, never modifies anything, and describes the exact output (human-readable findings or 'No real candidates found.'). It also discloses the pyproject.toml dependency for deptry and explains the confidence threshold's trade-off. No annotation contradiction.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact—three sentences for behavior plus two parameter explanations—and all content earns its place, with read-only status front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter tool with an output schema and a single sibling, this description covers input semantics, prerequisites, behavioral safety, and result format. The only omitted piece is explicit sibling differentiation, which belongs to usage guidelines. Combined with schema and output schema, an agent has everything needed to invoke it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema has 0% description coverage, and the description fills in all of it: repo_path is the path to the repository and must contain pyproject.toml for dependency checks, and min_confidence maps to vulture's 0-100 threshold with a false-positive trade-off. This goes well beyond the parameter names and defaults.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb-resource pair: scan a Python repository, and names the two tools (vulture, deptry) and the two classes of findings (dead code, dependency issues). This clearly distinguishes it from the sibling propose_removal_pr, whose action is proposing a PR, not scanning.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool versus propose_removal_pr, nor any when-not conditions. However, the read-only declaration and human-readable output imply this is an analysis step, and the requirement about pyproject.toml provides some context. This makes usage predictable but not explicitly ruled for alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 2 tool updatesv0.1.2
    • First observedpropose_removal_pr
    • First observedscan_dead_code

TDQS

A4.4/5.0

Scored across 2 tools

Disambiguation5/5

scan_dead_code is purely read-only analysis, while propose_removal_pr actually creates a branch and PR. Their purposes are complementary and unlikely to be confused.

Naming Consistency4/5

Both tool names use lower_snake verb-first conventions: scan_dead_code and propose_removal_pr. The pattern is predictable, though the second name is slightly less clean because 'removal_pr' bundles an action and an object into one noun phrase.

Tool Count3/5

Two tools is on the thin side and sits at the borderline of feeling complete. However, each tool has a distinct role in a focused analyze-then-propose workflow, so the small count is plausible for a narrow server.

Completeness3/5

The scan surfaces both dead code and dependency issues, but propose_removal_pr only handles unused imports. Dependency fixes and non-import dead-code removals are therefore dead ends, creating a notable gap in the advertised safe-fix domain.

Maintenance

ActivitySlowing
ResponsivenessNo issues

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