Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Description from the maker (original English)
Language servers as 66 code-intelligence tools for AI agents, CI-verified on 32 languages.
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Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json
{
"mcpServers": {
"agent-lsp": {
"command": "npx",
"args": [
"-y",
"@blackwell-systems/agent-lsp"
]
}
}
}Run this in your terminal
claude mcp add agent-lsp -- npx -y @blackwell-systems/agent-lspPaste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"agent-lsp": {
"command": "npx",
"args": [
"-y",
"@blackwell-systems/agent-lsp"
]
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Paste into .vscode/mcp.json in your project
{
"servers": {
"agent-lsp": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@blackwell-systems/agent-lsp"
]
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
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Runs on your computer; the tool list appears in your AI app after you install it.
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026
The registry name was verified with the GitHub account blackwell-systems, which owns the repo
We have not read this repo from GitHub yet
We have not read this repo from GitHub yet
This one runs on your computer; there is no internet endpoint
Runs on your computer and uses local settings instead
Runs on your computer; we can only read tool lists from internet endpoints
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
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It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).
The GitHub repo last changed –, and the latest version (0.24.2) reached the registry 3 days ago.
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.
In the same category: Spec Driven Development, Remote Desktop Commander, MemberVault MCP by usefulapi
Servers in the same category from other makers, sorted by stars.
Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
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Code intelligence infrastructure for AI agents. 66 tools, 32 CI-verified languages, 24 agent workflows. Single Go binary.
curl -fsSL https://raw.githubusercontent.com/blackwell-systems/agent-lsp/main/install.sh | sh && agent-lsp init
agent-lsp is an MCP server that orchestrates existing LSP servers (gopls, rust-analyzer, jdtls, etc.) into agent-native workflows.
Not an LSP server — it's an orchestration layer that manages language servers and exposes batch operations, speculative editing, and multi-step workflows via MCP tools.
Architecture:
Persistent warm runtime Language servers stay indexed across agent sessions. First session: indexes workspace (~10s for typical projects). Subsequent sessions: instant. No cold-start penalty on each request.
Batch operations blast_radius → one call returns all exports + all callers (test vs non-test partitioned). Without orchestration: 20+ sequential LSP calls.
Speculative editing simulate_edit → preview changes in memory, check diagnostic delta, apply or discard. Test edits before touching disk. safe_apply_edit writes only an edit it could verify: if the preview timed out or the server was still indexing, nothing is written.
Workflow orchestration 24 skills that chain LSP operations into complete pipelines:
/lsp-refactor → impact analysis → preview → apply → verify build → run tests/lsp-safe-edit → preview → diagnostic diff → apply if safe/lsp-verify → LSP diagnostics → build → test suiteMulti-language, single session One agent-lsp process routes .go to gopls, .ts to tsserver, .py to pyright. No reconfiguration between projects. Session persists across files and repositories. Workspace-wide queries (find_symbol, get_server_capabilities) ask every running language server, not just the default one. start_lsp can also connect to a language server that is already running (e.g. gopls -listen) and reuse its warm index.
[!TIP]
Token-optimized output: Tool responses encoded in GCF instead of JSON. 30-84% fewer tokens depending on tool (up to 92.7% with session dedup). 100% LLM comprehension on every frontier model, 91.2% on complex code graphs where JSON averages 54.1%. See below for measured savings per tool.
How the pieces fit together: LSP (Language Server Protocol) is how editors get code intelligence: completions, diagnostics, go-to-definition. MCP (Model Context Protocol) is the standard way AI tools like Claude Code discover and call external tools. agent-lsp bridges the two: language server intelligence, accessible to AI agents.
We asked AI agents to evaluate agent-lsp across 10 coding tasks (find callers, rename safely, preview edits, detect dead code) and write an honest assessment. Four different models, four independent evaluations, same conclusion:
Claude (Opus 4.6): "I would recommend agent-lsp for any workflow involving refactoring, impact analysis, or safe editing. The standout tools are
blast_radius(blast radius in one call, with test/non-test partitioning that would take 5-10 grep commands to replicate),go_to_implementation(type-checked interface satisfaction that grep simply cannot do), and the simulation session workflow (speculative type-checking without touching disk, which has no grep/read equivalent at all)."
Cursor (auto): "I would recommend agent-lsp for heavy refactors and code navigation because the rename, references, implementations, call hierarchy, and simulation tools remove a lot of brittle grep/manual-edit work and make changes safer."
GPT-5.5 (via Codex): "I would recommend agent-lsp for symbol-aware work: references, implementations, rename previews, diagnostics, and large-file structure are materially faster and less error-prone than grep/read loops."
Gemini 2.5 Pro (via Gemini CLI): "I would highly recommend agent-lsp because it provides a level of semantic awareness that standard text-searching tools simply cannot match. The ability to perform high-confidence renames, find interface implementations, and preview the diagnostic impact of edits without writing to disk significantly reduces the risk of introducing regressions."
Every other MCP-LSP implementation lists supported languages in a config file. None of them run the actual language server in CI to verify it works.
agent-lsp CI runs 32 real language servers against real fixture codebases on every push, and all 32 pass end to end: Go, Python, TypeScript, Rust, Java, C, C++, C#, Ruby, PHP, Kotlin, Swift, Scala, Zig, Lua, Elixir, Gleam, Clojure, Dart, Terraform, Nix, Prisma, SQL, MongoDB, MQL, and more. When we say "works with gopls," that's a verified, automated claim, not a hope.
Simulate changes in memory before writing to disk. No other MCP-LSP implementation has this.
preview_edit previews the diagnostic impact of any edit. You see exactly what breaks before the file is touched. simulate_chain evaluates a sequence of dependent edits (rename a function, update all callers, change the return type) and reports which step first introduces an error.
8 speculative execution tools. See docs/guide/speculative-execution.md for the full workflow.
Some refactorings need answers before the language server can compute them: which struct tags to add and how to name them, which interface to implement, where a declaration should move. gopls v0.24 asks these questions through a new LSP extension (golang/go#76331), which editors show as dialogs. agent-lsp is a client for it built for agents: refactor returns the questions as a typed form (choices, defaults, a searchable list for the interface), the agent answers, and the server computes the edit. agent-lsp captures that edit before it is written, so dry_run previews it.
refactor(file, line, column) → available refactorings
refactor(..., action: "Add struct tags") → questions: tags (default "json"), naming style (camelCase, snake_case, ...) refactor(..., answers: {addTags: "json", transform: "snakecase"}) → applied
See refactor in the tool reference.
Structured LSP responses use 5-34x fewer tokens than grep/read on the same tasks. On HashiCorp Consul (319K lines), a blast-radius analysis uses 17.7MB via grep vs 841KB via LSP, reducing 5,534 tool calls to 119. Savings scale with codebase size. See docs/guide/token-savings.md for the full experiment across five codebases.
Tool responses are encoded in GCF (Graph Compact Format) instead of JSON. GCF eliminates field-name repetition, identifier repetition, and per-record structural overhead.
| Profile | Tools | Savings vs JSON |
|---|---|---|
| Tabular | Other structured results (find_references, diagnostics, detect_changes, ...) | 30-51% |
| Graph | list_symbols, find_symbol, blast_radius, find_callers, explore_symbol, type_hierarchy, get_cross_repo_references | 79-84% |
| Graph + session dedup | Same, via gcf-proxy --session | 92.7% (5th call) |
Workspace edits (rename and refactor previews) are always JSON, so they round-trip into apply_edit byte-exact. Grouped/nested responses (callers under a symbol, diagnostics with related info) tabularize too, for ~14% over JSON on that shape (details).
GCF is enabled by default. To revert to JSON:
export AGENT_LSP_OUTPUT_FORMAT=json
Benchmark: go run scripts/gcf-benchmark.go. See docs/guide/gcf-integration.md for architecture details.
GCF: gcformat.com · Spec · Go · Python · TypeScript · Playground
AI agents make incorrect code changes because they can't see the full picture: who calls this function, what breaks if I rename it, does the build still pass. Language servers have the answers, but raw LSP tools require 20+ sequential calls and complex orchestration logic.
agent-lsp solves this by encoding correct multi-step operations into single calls and skills. blast_radius does what would take an agent 20+ calls in one. /lsp-refactor chains impact → preview → apply → verify → test without per-prompt orchestration.
Python and TypeScript projects need minutes of background indexing before find_references works. agent-lsp automatically spawns a persistent daemon broker that survives between sessions, so the workspace stays indexed. First session: daemon starts and indexes (~10s for FastAPI). Subsequent sessions: instant connection to the warm daemon. Auto-exits after 30 minutes of inactivity. Go, Rust, and other fast-indexing languages bypass this entirely (zero overhead).
Skills tell agents the correct order of operations. Phase enforcement makes the runtime *block* violations instead of trusting the agent to follow instructions.
When an agent activates a skill, every tool call is checked agains
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