mcp-language-server MCP — Cas d'usage, Installer & Démo en direct

Pourquoi l'utiliser

Fonctionnalités clés

LSP semantic operations: definition, references, rename, hover, diagnostics
Works with any stdio LSP (gopls, rust-analyzer, pyright, tsserver, clangd)
Single Go binary, easy install
edit_file uses LSP-backed rename for correctness
One MCP instance per LSP; compose multiple for polyglot repos

Démo en direct

Aperçu en pratique

language-server.replay ▶ prêt

0/0

Installer

Choisissez votre client

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "language-server": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/isaacphi/mcp-language-server"
      ],
      "_inferred": true
    }
  }
}

Ouvrez Claude Desktop → Settings → Developer → Edit Config. Redémarrez après avoir enregistré.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "language-server": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/isaacphi/mcp-language-server"
      ],
      "_inferred": true
    }
  }
}

Cursor utilise le même schéma mcpServers que Claude Desktop. La config projet l'emporte sur la globale.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "language-server": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/isaacphi/mcp-language-server"
      ],
      "_inferred": true
    }
  }
}

Cliquez sur l'icône MCP Servers dans la barre latérale Cline, puis "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "language-server": {
      "command": "TODO",
      "args": [
        "See README: https://github.com/isaacphi/mcp-language-server"
      ],
      "_inferred": true
    }
  }
}

Même format que Claude Desktop. Redémarrez Windsurf pour appliquer.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "language-server",
      "command": "TODO",
      "args": [
        "See README: https://github.com/isaacphi/mcp-language-server"
      ]
    }
  ]
}

Continue utilise un tableau d'objets serveur plutôt qu'une map.

~/.config/zed/settings.json

{
  "context_servers": {
    "language-server": {
      "command": {
        "path": "TODO",
        "args": [
          "See README: https://github.com/isaacphi/mcp-language-server"
        ]
      }
    }
  }
}

Ajoutez dans context_servers. Zed recharge à chaud à la sauvegarde.

claude mcp add language-server -- TODO 'See README: https://github.com/isaacphi/mcp-language-server'

Une seule ligne. Vérifiez avec claude mcp list. Supprimez avec claude mcp remove.

Cas d'usage

Usages concrets : mcp-language-server

How to rename a symbol safely across a repo

👤 Polyglot devs using agents ⏱ ~15 min intermediate

Quand l'utiliser : You want a rename that understands scope, not a find-replace.

Prérequis

Go installed — brew install go
The LSP for your language — gopls: go install golang.org/x/tools/gopls@latest; pyright: pip install pyright; etc.
Install the MCP — go install github.com/isaacphi/mcp-language-server@latest

Déroulement

Start the MCP pointed at your workspace + LSP

Add MCP config: command=mcp-language-server, args=['--workspace','.','--lsp','gopls'].✓ Copié

→ Tools appear
Find references first

references for symbol 'LegacyAuth' in file auth.go.✓ Copié

→ Precise cross-repo references
Rename

rename_symbol 'LegacyAuth' -> 'Auth' at the definition site.✓ Copié

→ All callsites updated correctly

Résultat : Semantically-correct rename across the repo.

Pièges

Agent falls back to text find-replace when the tool fails — Verify diagnostics after rename — compile errors mean the LSP refused and the agent cheated

Combiner avec : github

How to let the agent navigate like you do in an IDE

👤 Agent users tired of re-grepping ⏱ ~10 min beginner

Quand l'utiliser : Agent keeps reading whole files to find one function.

Déroulement

Query definition

definition for 'computeTax' in src/billing.ts.✓ Copié

→ Exact file:line location
Pull diagnostics

diagnostics for the current file.✓ Copié

→ Red squigglies from the LSP

Résultat : Agent navigates like an IDE user.

Pièges

LSP not initialized — slow first call — Warm up with a list of files in the workspace; pyright especially is slow to index

Combiner avec : contextplus

How to run multiple LSPs for a polyglot monorepo

👤 Devs on Go+TS+Python monorepos ⏱ ~25 min advanced

Quand l'utiliser : You want semantic ops in every language.

Déroulement

Register one MCP per LSP

Add 3 MCP entries: lsp-go (gopls), lsp-ts (tsserver), lsp-py (pyright), each scoped to its workspace subfolder.✓ Copié

→ 3 sets of language-specific tools
Use them in turn

For TypeScript questions use lsp-ts:definition; for Go use lsp-go:definition.✓ Copié

→ Correct semantics per language

Résultat : Semantically-aware navigation across all languages.

Pièges

Agent forgets which MCP handles which language — Rename tool prefixes descriptively and mention in your project memory

Combinaisons

Associez-le à d'autres MCPs pour un effet X10

language-server + contextplus

Combine LSP navigation with semantic/embedding search for broader queries

Use language-server's references for exact usages of computeTax, then contextplus semantic search to find conceptually-related functions.✓ Copié

language-server + github

Rename + commit + PR

Rename LegacyAuth to Auth via the LSP, commit to a new branch, open a PR.✓ Copié

Outils

Ce que ce MCP expose

Outil	Entrées	Quand appeler	Coût
definition	file: str, symbol_or_position	Jump to declaration	free (local LSP)
references	file: str, symbol_or_position	Find usages	free
diagnostics	file: str	Check errors/warnings	free
hover	file, position	Type info / docs for a symbol	free
rename_symbol	file, position, new_name	Safe rename	free
edit_file	file, edits	LSP-validated edit	free

Coût et limites

Coût d'exécution

Quota d'API: None — local LSP
Tokens par appel: Small — LSP responses are compact
Monétaire: Free
Astuce: Use LSP-backed tools before embedding search — often cheaper and more precise.

Sécurité

Permissions, secrets, portée

Portées minimales : Filesystem read/write to the workspace

Stockage des identifiants : None

Sortie de données : Localhost only; LSP runs in-process

Ne jamais accorder : Don't point it at workspaces with secrets — LSPs sometimes index them

edit_file respects LSP validation but doesn't guarantee atomicity across multi-file edits.

Dépannage

Erreurs courantes et correctifs

tool returns 'LSP not ready'

First call triggers initialization — retry after 2-5 seconds, or warm up with a hover call.

gopls: 'no packages found'

Point workspace at the module root (where go.mod is), not a subfolder.

Vérifier : go env GOMOD

pyright slow on big repos

Configure pyrightconfig.json to exclude vendored dirs.

rename_symbol reports success but compile still fails

Rename touched a string literal or reflection-based code the LSP can't see. Check grep for the old name.

Alternatives

mcp-language-server vs autres

Alternative	Quand l'utiliser	Compromis
Context+	You want embedding + memory graph rather than LSP semantics	Not as precise on rename/references
Serena MCP	You want LSP with higher-level refactors	Different setup; Python-based

Plus

Ressources

📖 Lire le README officiel sur GitHub

🐙 Voir les issues ouvertes

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