feat(cli/mcp): an initial implementation of a lit mcp server package #4990

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

⏳ Benchmarks are currently running. Results below are out of date.

nop-update

this-change, tip-of-tree, previous-release: unsure 🔍 -11% - +8% (-1.50ms - +1.05ms)
^{this-change vs tip-of-tree}

render

this-change: 50.30ms - 67.55ms
this-change, tip-of-tree, previous-release: unsure 🔍 -3% - +4% (-0.57ms - +0.78ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: faster ✔ 1% - 3% (0.19ms - 1.06ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -24% - +29% (-12.89ms - +15.46ms)
^{this-change vs tip-of-tree}

update

this-change: 486.22ms - 495.84ms
this-change, tip-of-tree, previous-release: unsure 🔍 -6% - +4% (-2.42ms - +1.76ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -4% - +1% (-3.60ms - +0.78ms)
^{this-change vs tip-of-tree}
this-change, tip-of-tree, previous-release: unsure 🔍 -2% - +1% (-9.55ms - +3.47ms)
^{this-change vs tip-of-tree}

update-reflect

this-change: 471.85ms - 479.47ms
this-change, tip-of-tree, previous-release: unsure 🔍 -1% - +2% (-5.53ms - +8.17ms)
^{this-change vs tip-of-tree}

Results

⏳ Benchmarks are currently running. Results below are out of date.

this-change

Browser: chrome-headless 136.0.0.0
Sample size: 50
Built by: Benchmarks #6799
Commit: 360aa0f

render

Version	Avg time	vs
	50.30ms - 67.55ms	-

update

Version	Avg time	vs
	486.22ms - 495.84ms	-

update-reflect

Version	Avg time	vs
	471.85ms - 479.47ms	-

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

Browser: chrome-headless 136.0.0.0
Sample size: 30
Built by: Benchmarks #6799
Commit: 360aa0f

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	19.22ms - 20.13ms	-	unsure 🔍 -3% - +4% -0.57ms - +0.78ms	unsure 🔍 -3% - +3% -0.65ms - +0.62ms
tip-of-tree tip-of-tree	19.08ms - 20.06ms	unsure 🔍 -4% - +3% -0.78ms - +0.57ms	-	unsure 🔍 -4% - +3% -0.78ms - +0.54ms
previous-release previous-release	19.25ms - 20.13ms	unsure 🔍 -3% - +3% -0.62ms - +0.65ms	unsure 🔍 -3% - +4% -0.54ms - +0.78ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	37.63ms - 40.59ms	-	unsure 🔍 -6% - +4% -2.42ms - +1.76ms	unsure 🔍 -5% - +5% -1.82ms - +2.05ms
tip-of-tree tip-of-tree	37.97ms - 40.92ms	unsure 🔍 -5% - +6% -1.76ms - +2.42ms	-	unsure 🔍 -4% - +6% -1.49ms - +2.37ms
previous-release previous-release	37.75ms - 40.25ms	unsure 🔍 -5% - +5% -2.05ms - +1.82ms	unsure 🔍 -6% - +4% -2.37ms - +1.49ms	-

nop-update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	11.99ms - 13.75ms	-	unsure 🔍 -11% - +8% -1.50ms - +1.05ms	unsure 🔍 -12% - +5% -1.67ms - +0.75ms
tip-of-tree tip-of-tree	12.17ms - 14.02ms	unsure 🔍 -8% - +12% -1.05ms - +1.50ms	-	unsure 🔍 -11% - +7% -1.47ms - +1.01ms
previous-release previous-release	12.50ms - 14.15ms	unsure 🔍 -6% - +13% -0.75ms - +1.67ms	unsure 🔍 -8% - +11% -1.01ms - +1.47ms	-

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

Browser: chrome-headless 136.0.0.0
Sample size: 50
Built by: Benchmarks #6799
Commit: 360aa0f

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	35.56ms - 36.12ms	-	faster ✔ 1% - 3% 0.19ms - 1.06ms	unsure 🔍 -2% - +1% -0.56ms - +0.27ms
tip-of-tree tip-of-tree	36.13ms - 36.80ms	slower ❌ 1% - 3% 0.19ms - 1.06ms	-	slower ❌ 0% - 3% 0.02ms - 0.93ms
previous-release previous-release	35.68ms - 36.29ms	unsure 🔍 -1% - +2% -0.27ms - +0.56ms	faster ✔ 0% - 3% 0.02ms - 0.93ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	77.01ms - 79.81ms	-	unsure 🔍 -4% - +1% -3.60ms - +0.78ms	unsure 🔍 -2% - +2% -1.90ms - +1.83ms
tip-of-tree tip-of-tree	78.13ms - 81.50ms	unsure 🔍 -1% - +5% -0.78ms - +3.60ms	-	unsure 🔍 -1% - +4% -0.72ms - +3.46ms
previous-release previous-release	77.22ms - 79.68ms	unsure 🔍 -2% - +2% -1.83ms - +1.90ms	unsure 🔍 -4% - +1% -3.46ms - +0.72ms	-

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

Browser: chrome-headless 136.0.0.0
Sample size: 50
Built by: Benchmarks #6799
Commit: 360aa0f

render

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	45.96ms - 66.14ms	-	unsure 🔍 -24% - +29% -12.89ms - +15.46ms	unsure 🔍 -27% - +22% -15.56ms - +12.87ms
tip-of-tree tip-of-tree	44.81ms - 64.72ms	unsure 🔍 -27% - +23% -15.46ms - +12.89ms	-	unsure 🔍 -29% - +19% -16.76ms - +11.49ms
previous-release previous-release	47.38ms - 67.41ms	unsure 🔍 -23% - +28% -12.87ms - +15.56ms	unsure 🔍 -22% - +31% -11.49ms - +16.76ms	-

update

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	481.32ms - 490.00ms	-	unsure 🔍 -2% - +1% -9.55ms - +3.47ms	unsure 🔍 -1% - +2% -6.54ms - +7.90ms
tip-of-tree tip-of-tree	483.86ms - 493.56ms	unsure 🔍 -1% - +2% -3.47ms - +9.55ms	-	unsure 🔍 -1% - +2% -3.82ms - +11.26ms
previous-release previous-release	479.22ms - 490.75ms	unsure 🔍 -2% - +1% -7.90ms - +6.54ms	unsure 🔍 -2% - +1% -11.26ms - +3.82ms	-

update-reflect

Version	Avg time	vs this-change	vs tip-of-tree tip-of-tree	vs previous-release previous-release
this-change	491.80ms - 502.01ms	-	unsure 🔍 -1% - +2% -5.53ms - +8.17ms	unsure 🔍 -3% - +1% -13.09ms - +5.63ms
tip-of-tree tip-of-tree	491.01ms - 500.16ms	unsure 🔍 -2% - +1% -8.17ms - +5.53ms	-	unsure 🔍 -3% - +1% -14.13ms - +4.04ms
previous-release previous-release	492.78ms - 508.48ms	unsure 🔍 -1% - +3% -5.63ms - +13.09ms	unsure 🔍 -1% - +3% -4.04ms - +14.13ms	-

_{tachometer-reporter-action v2 for Benchmarks}

changeset-bot · 2025-05-17T02:03:46Z

🦋 Changeset detected

Latest commit: 87f31d3

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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Click here if you're a maintainer who wants to add another changeset to this PR

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

View reviewed changes

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

87f31d3

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 360aa0f to 87f31d3 Compare June 18, 2025 20:04

e111077 6D40 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

feat(cli/mcp): an initial implementation of a lit mcp server package #4990

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📊 Tachometer Benchmark Results

Summary

nop-update

render

update

update-reflect

Results

render

update

update-reflect

render

update

nop-update

render

update

render

update

update-reflect

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