feat(cli/mcp): an initial implementation of a lit mcp server package by e111077 · Pull Request #4990 · lit/lit

e111077 · 2025-05-17T01:58:43Z

This implements a very basic mcp server that hooks into our algolia search for lit.dev. The key exposed is a rate-limited read-only key.

Features in this pr:

Implements an mcp server
- Tools can have environment compatibilities
  - local can only run when it has source code in front of it or on a local machine
    - e.g. a tool that runs lit analyzer on your code
  - server can only run when it's on a server
    - e.g. a tool potentially set up at an endpoint on something like lit.dev/mcp that might require special API keys etc
  - any can run in any environment
    - e.g. a tool that can run on either local or server like algolia search
- Only has an algolia search tool right now. Would be cool to eventually search discord
Implements the lit labs mcp command
- Adds this as a labs command on the lit CLI
- Implement the --skip-permissions command so that AI tools don't get stuck on the cli asking to install the mcp server

Parent	Children
#4970

github-actions · 2025-05-17T01:58:56Z

📊 Tachometer Benchmark Results

Summary

nop-update

this-change, tip-of-tree, previous-release: unsure 🔍 -4% - +7% (-0.46ms - +0.76ms)
^{this-change vs tip-of-tree}

render

this-change: 42.64ms - 54.27ms
this-change, tip-of-tree, previous-release: unsure 🔍 -3% - +5% (-0.67ms - +0.93ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -1% - +3% (-0.34ms - +1.14ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -20% - +36% (-8.36ms - +15.52ms)
^{this-change vs tip-of-tree}

update

this-change: 465.62ms - 474.21ms
this-change, tip-of-tree, previous-release: unsure 🔍 -3% - +9% (-1.10ms - +3.22ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -0% - +6% (+0.02ms - +4.07ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -1% - +1% (-6.94ms - +4.55ms)
^{this-change vs tip-of-tree}

update-reflect

this-change: 457.20ms - 464.49ms
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +1% (-8.43ms - +4.67ms)
^{this-change vs tip-of-tree}

Results

this-change

Browser: chrome-headless 139.0.0.0
Sample size: 50
Built by: Benchmarks #6892
Commit: 8c71d96

render

Version	Avg time	vs
	42.64ms - 54.27ms	-

update

Version	Avg time	vs
	465.62ms - 474.21ms	-

update-reflect

Version	Avg time	vs
	457.20ms - 464.49ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 139.0.0.0
Sample size: 30
Built by: Benchmarks #6892
Commit: 8c71d96

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	19.16ms - 20.19ms	-	unsure 🔍 -3% - +5% -0.67ms - +0.93ms	unsure 🔍 -3% - +4% -0.63ms - +0.87ms
tip-of-tree tip-of-tree	18.94ms - 20.15ms	unsure 🔍 -5% - +3% -0.93ms - +0.67ms	-	unsure 🔍 -4% - +4% -0.82ms - +0.80ms
previous-release previous-release	19.02ms - 20.10ms	unsure 🔍 -4% - +3% -0.87ms - +0.63ms	unsure 🔍 -4% - +4% -0.80ms - +0.82ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	35.48ms - 38.16ms	-	unsure 🔍 -3% - +9% -1.10ms - +3.22ms	unsure 🔍 -5% - +7% -1.72ms - +2.46ms
tip-of-tree tip-of-tree	34.07ms - 37.45ms	unsure 🔍 -9% - +3% -3.22ms - +1.10ms	-	unsure 🔍 -8% - +4% -3.02ms - +1.64ms
previous-release previous-release	34.85ms - 38.06ms	unsure 🔍 -7% - +5% -2.46ms - +1.72ms	unsure 🔍 -5% - +9% -1.64ms - +3.02ms	-

nop-update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	11.03ms - 11.96ms	-	unsure 🔍 -4% - +7% -0.46ms - +0.76ms	unsure 🔍 -5% - +6% -0.59ms - +0.70ms
tip-of-tree tip-of-tree	10.95ms - 11.74ms	unsure 🔍 -7% - +4% -0.76ms - +0.46ms	-	unsure 🔍 -6% - +4% -0.69ms - +0.50ms
previous-release previous-release	10.99ms - 11.89ms	unsure 🔍 -6% - +5% -0.70ms - +0.59ms	unsure 🔍 -4% - +6% -0.50ms - +0.69ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 139.0.0.0
Sample size: 50
Built by: Benchmarks #6892
Commit: 8c71d96

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	35.36ms - 36.41ms	-	unsure 🔍 -1% - +3% -0.34ms - +1.14ms	unsure 🔍 -1% - +4% -0.18ms - +1.25ms
tip-of-tree tip-of-tree	34.96ms - 36.00ms	unsure 🔍 -3% - +1% -1.14ms - +0.34ms	-	unsure 🔍 -2% - +2% -0.59ms - +0.85ms
previous-release previous-release	34.86ms - 35.84ms	unsure 🔍 -3% - +0% -1.25ms - +0.18ms	unsure 🔍 -2% - +2% -0.85ms - +0.59ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	72.68ms - 75.80ms	-	unsure 🔍 -0% - +6% +0.02ms - +4.07ms	unsure 🔍 -2% - +4% -1.15ms - +2.81ms
tip-of-tree tip-of-tree	70.90ms - 73.49ms	faster ✔ 0% - 5% 0.02ms - 4.07ms	-	unsure 🔍 -4% - +1% -3.00ms - +0.57ms
previous-release previous-release	72.18ms - 74.63ms	unsure 🔍 -4% - +2% -2.81ms - +1.15ms	unsure 🔍 -1% - +4% -0.57ms - +3.00ms	-

this-change, tip-of-tree, previous-release

Browser: chrome-headless 139.0.0.0
Sample size: 50
Built by: Benchmarks #6892
Commit: 8c71d96

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	38.68ms - 56.50ms	-	unsure 🔍 -20% - +36% -8.36ms - +15.52ms	unsure 🔍 -34% - +12% -19.02ms - +7.40ms
tip-of-tree tip-of-tree	36.06ms - 51.96ms	unsure 🔍 -32% - +17% -15.52ms - +8.36ms	-	unsure 🔍 -39% - +4% -21.97ms - +3.19ms
previous-release previous-release	43.65ms - 63.15ms	unsure 🔍 -17% - +42% -7.40ms - +19.02ms	unsure 🔍 -10% - +52% -3.19ms - +21.97ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	486.57ms - 494.92ms	-	unsure 🔍 -1% - +1% -6.94ms - +4.55ms	unsure 🔍 -1% - +1% -6.43ms - +5.02ms
tip-of-tree tip-of-tree	487.99ms - 495.88ms	unsure 🔍 -1% - +1% -4.55ms - +6.94ms	-	unsure 🔍 -1% - +1% -5.07ms - +6.05ms
previous-release previous-release	487.53ms - 495.36ms	unsure 🔍 -1% - +1% -5.02ms - +6.43ms	unsure 🔍 -1% - +1% -6.05ms - +5.07ms	-

update-reflect

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	489.58ms - 498.96ms	-	unsure 🔍 -2% - +1% -8.43ms - +4.67ms	unsure 🔍 -2% - +0% -9.48ms - +2.09ms
tip-of-tree tip-of-tree	491.59ms - 500.72ms	unsure 🔍 -1% - +2% -4.67ms - +8.43ms	-	unsure 🔍 -2% - +1% -7.50ms - +3.87ms
previous-release previous-release	494.59ms - 501.35ms	unsure 🔍 -0% - +2% -2.09ms - +9.48ms	unsure 🔍 -1% - +2% -3.87ms - +7.50ms	-

_{tachometer-reporter-action v2 for Benchmarks}

changeset-bot · 2025-05-17T02:03:46Z

🦋 Changeset detected

Latest commit: 8c71d96

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@lit-labs/cli-mcp-server	Minor
@lit-labs/cli	Minor

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e111077 · 2025-05-17T02:41:51Z

I had issues writing tests for this. The CLI version of this package seems to be the only way we can test this with with CI. Issues are:

Do we want to include network requests in our tests?
Invoking it from within the directory with npx ran into version conflicts with a transitive commander dependency:

npx @modelcontextprotocol/inspector --cli --help # program.name(...).allowExcessArguments is not a function

github-actions · 2025-05-17T02:56:43Z

The size of lit-html.js and lit-core.min.js are as expected.

rictic

Nice!

packages/labs/mcp-server/src/index.ts

packages/labs/mcp-server/src/search-lit-dev.ts

packages/labs/vue-utils/src/wrapper-utils.ts

.changeset/witty-masks-begin.md

.changeset/lovely-mangos-deny.md

e111077 · 2025-06-05T22:50:49Z

@rictic PTAL: I've made some changes by adding this to the Lit CLI. I've updated the PR description

packages/labs/cli-mcp-server/package.json

packages/labs/cli/README.md

rictic · 2025-06-18T01:23:09Z

packages/labs/cli-mcp-server/src/index.ts

+          'The environment to run in, either "local" or "server". Server mode will ' +
+          'only expose MCP commands that are available on the server which are commands that do ' +
+          'not require local file access.',
+        typeLabel: '"local", "server"',


What local filesystem tools are you thinking of?

This is what we were discussing previously:

Local, requires filesysten access like generating / finding CE manifests

Server, only requires network access to enable a RAG via MCP over HTTP (such as site search)

This implements a very basic mcp server that hooks into our algolia search for lit.dev. The key exposed is a rate-limited read-only key.

e111077 mentioned this pull request May 17, 2025

style(copilot-instructions): add a copilot instructions file #4970

Merged

e111077 force-pushed the copilot-instructions branch from 256df49 to ef0d45c Compare May 17, 2025 02:03

e111077 force-pushed the mcp-server branch from 9166d5b to 3f003d1 Compare May 17, 2025 02:03

e111077 force-pushed the copilot-instructions branch from ef0d45c to 2213cb5 Compare May 17, 2025 02:04

e111077 force-pushed the mcp-server branch from 3f003d1 to 3759dea Compare May 17, 2025 02:04

e111077 marked this pull request as ready for review May 17, 2025 02:05

e111077 requested a review from kevinpschaaf as a code owner May 17, 2025 02:05

e111077 force-pushed the copilot-instructions branch from 2213cb5 to a81b2a8 Compare May 17, 2025 02:54

e111077 force-pushed the mcp-server branch from 3759dea to 5a2fc66 Compare May 17, 2025 02:54

e111077 force-pushed the copilot-instructions branch from a81b2a8 to 42f84b1 Compare May 17, 2025 02:59

e111077 force-pushed the mcp-server branch from 5a2fc66 to dee561e Compare May 17, 2025 02:59

e111077 force-pushed the copilot-instructions branch from 42f84b1 to 83e7f0b Compare May 17, 2025 04:13

e111077 force-pushed the mcp-server branch from dee561e to b104d6d Compare May 17, 2025 04:14

Base automatically changed from copilot-instructions to main May 19, 2025 06:09

e111077 requested a review from justinfagnani May 19, 2025 06:10

rictic reviewed Jun 5, 2025

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e111077 force-pushed the mcp-server branch from b104d6d to 4e71642 Compare June 5, 2025 18:09

e111077 changed the title ~~[mcp-server] an initial implementation of a lit mcp server package~~ feat(mcp): an initial implementation of a lit mcp server package Jun 5, 2025

e111077 force-pushed the mcp-server branch 3 times, most recently from fd29310 to a312af9 Compare June 5, 2025 22:40

e111077 changed the title ~~feat(mcp): an initial implementation of a lit mcp server package~~ feat(clit/mcp): an initial implementation of a lit mcp server package Jun 5, 2025

e111077 requested a review from rictic June 5, 2025 22:46

e111077 force-pushed the mcp-server branch 2 times, most recently from 4353115 to eadf6f8 Compare June 5, 2025 22:50

e111077 force-pushed the mcp-server branch from eadf6f8 to 360aa0f Compare June 5, 2025 22:51

rictic reviewed Jun 18, 2025

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e111077 force-pushed the mcp-server branch from 360aa0f to 87f31d3 Compare June 18, 2025 20:04

e111077 changed the title ~~feat(clit/mcp): an initial implementation of a lit mcp server package~~ feat(cli/mcp): an initial implementation of a lit mcp server package Jun 19, 2025

e111077 force-pushed the mcp-server branch 3 times, most recently from a5ef0ac to ca405be Compare August 21, 2025 18:48

[mcp-server] an initial implementation of a lit mcp server package

8c71d96

This implements a very basic mcp server that hooks into our algolia search for lit.dev. The key exposed is a rate-limited read-only key.

e111077 force-pushed the mcp-server branch from ca405be to 8c71d96 Compare August 21, 2025 22:10

e111077 enabled auto-merge (rebase) August 21, 2025 22:28

rictic approved these changes Aug 21, 2025

View reviewed changes

e111077 merged commit 36c6c00 into main Aug 21, 2025
10 checks passed

e111077 deleted the mcp-server branch August 21, 2025 22:32

lit-robot mentioned this pull request Dec 18, 2025

Version Packages #5183

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📊 Tachometer Benchmark Results

Summary

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