language-server-mcp-rs

An MCP server that exposes rust-analyzer capabilities (via MCP tools) so AI assistants can query Rust code for types, diagnostics, completions, definitions, references, formatting, refactors, and macro expansion in a workspace.

Evaluated Apr 04, 2026 (16d ago)

Repo ↗ DevTools mcp rust language-server lsp code-assistant refactoring

⚙ Agent Friendliness

/ 100

Can an agent use this?

🔒 Security

/ 100

Is it safe for agents?

⚡ Reliability

/ 100

Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality

Documentation

Error Messages

Auth Simplicity

Rate Limits

🔒 Security

TLS Enforcement

Auth Strength

Scope Granularity

Dep. Hygiene

Secret Handling

No authentication described; stdio/local deployment implies trust in the local host/assistant integration. The README does not mention TLS (not applicable to stdio) or secret handling. Dependency hygiene and secure error handling cannot be assessed from the provided README/metadata.

⚡ Reliability

Uptime/SLA

Version Stability

Breaking Changes

Error Recovery

Best When

You want an AI assistant to interact with a local Rust codebase using rust-analyzer features through MCP/stdio.

Avoid When

You cannot run local processes, need strong centralized access control/authentication, or require documented retry/idempotency guarantees for all tools.

Use Cases

• Ask an AI assistant for Rust type info at a file position (hover-like queries)
• Get compiler diagnostics for a Rust file via MCP tools
• Request code completions, inlay hints, and macro expansions for Rust projects
• Perform navigation/refactoring tasks such as goto definition, find references, and safe symbol rename across a workspace

Not For

• Production web/API use without running a local process (it is intended to be launched by a desktop/assistant host)
• Use as a general-purpose code search/indexer for non-Rust projects
• Use where enterprise auth, audit logging, or managed hosting requirements mandate a hosted API

Interface

REST API

GraphQL

gRPC

MCP Server

Yes

SDK

Webhooks

Authentication

OAuth: No Scopes: No

The README shows stdio-based MCP usage and does not describe any authentication mechanism. Access is implicitly local/host-controlled.

Pricing

Free tier: No

Requires CC: No

No pricing information provided; appears to be a self-hosted open-source tool.

Agent Metadata

Pagination

none

Idempotent

False

Retry Guidance

Not documented

Known Gotchas

⚠ Some tools (e.g., rename, code_actions) may modify workspace state; an agent should confirm before applying changes.
⚠ All coordinates (line/column) are 0-indexed per the README; mismatched indexing can lead to incorrect results.
⚠ Relies on a running rust-analyzer subprocess and correct workspace path; misconfiguration will prevent tool functionality.

Alternatives

Use rust-analyzer directly with an LSP-capable editor or extension Use other MCP servers that wrap LSP functionality for languages (if available) Build a custom MCP wrapper around rust-analyzer/rustc tooling

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Scores are editorial opinions as of 2026-04-04.