feat: expose product docs through MCP

[Kikobeats]

Goal

Add a microlink_docs MCP tool so agents can fetch the complete parameter documentation for a Microlink product before calling a product tool they do not know well.

Design

• Expose the existing core docs loader through the microlink.io/cli entry point.
• Register microlink_docs({ product }) in @microlink/mcp.
• Constrain product to the 20 products supported by the CLI.
• Return an actionable validation error for unknown products, including the valid product list.
• Keep existing product tool descriptions unchanged.

One source of truth

The new tool does not copy or generate product documentation. It calls the same loader used by microlink <product> docs, which fetches https://microlink.io/docs/sdk/methods/<product>.md. This keeps microlink.io as the canonical documentation source and prevents the MCP package from drifting.

Tool contract

microlink_docs({ product }) -> markdown string

Valid products: metadata, logo, markdown, html, text, video, audio, emails, links, images, videos, audios, extract, screenshot, pdf, embed, technologies, lighthouse, search, function.

The tool is read-only and declares a string output schema.

How to verify

pnpm run lint
pnpm --filter microlink.io test
pnpm --filter @microlink/mcp test
pnpm test

The MCP tests mock fetch and cover the happy path, unknown products, and fetch failures.

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Note

Low Risk
Read-only documentation fetch with no API-key or billing path; main risk is runtime dependency on microlink.io doc URLs staying available.

Overview
Adds microlink_docs to the MCP server so agents can pull canonical parameter documentation for a Microlink product before calling other product tools.

Core (microlink.io): Publishes a new microlink.io/docs export with the existing docs loader, a fixed products list (20 names), and a test that products stays aligned with library method keys.

MCP: Registers microlink_docs({ product }), which fetches the same markdown as microlink <product> docs from https://microlink.io/docs/sdk/methods/<product>.md. product is validated via the shared products enum (unknown values get an error listing valid choices). Output is a markdown string; default server instructions and README document the tool. Tests cover success, validation, and fetch failures.

^{Reviewed by Cursor Bugbot for commit f4f14d1. Bugbot is set up for automated code reviews on this repo. Configure here.}

Summary by CodeRabbit

• New Features

  • Added the microlink_docs tool for retrieving canonical Markdown documentation for supported products.
  • Added product validation with clear feedback when an unsupported product is requested.
  • Added a public documentation export listing available SDK products.
  • The tool now appears as Product docs and returns a defined Markdown response.

• Documentation

  • Updated MCP guidance and README content with usage details, supported products, parameters, and response behavior.
  • Added guidance to consult product documentation when tool parameters are unclear.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 94641bf3-ab8d-4da7-9635-bfa0e5127b44

📥 Commits

Reviewing files that changed from the base of the PR and between d20517d and f4f14d1.

📒 Files selected for processing (13)

• packages/core/bin/docs.js
• packages/core/package.json
• packages/core/test/docs.mjs
• packages/mcp/README.md
• packages/mcp/src/index.js
• packages/mcp/src/output-schemas.js
• packages/mcp/src/schemas.js
• packages/mcp/src/tools/docs.js
• packages/mcp/src/tools/index.js
• packages/mcp/src/tools/register.js
• packages/mcp/test/docs.test.js
• packages/mcp/test/stdio-server.test.js
• packages/mcp/test/tools.test.js

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

Changes

Product documentation access

Layer / File(s)	Summary
Core documentation export packages/core/bin/docs.js, packages/core/package.json, packages/core/test/docs.mjs	The core package exports the SDK product list through ./docs. A test verifies that the list matches the SDK method catalog.
MCP documentation contract and loader packages/mcp/src/schemas.js, packages/mcp/src/output-schemas.js, packages/mcp/src/tools/docs.js	The MCP package validates the required product, declares a string output, and loads product markdown through productDocs.load(product).
MCP registration and guidance packages/mcp/src/tools/index.js, packages/mcp/src/tools/register.js, packages/mcp/src/index.js, packages/mcp/README.md	The microlink_docs tool is registered with the title Product docs. Instructions and README content describe when and how to call it.
MCP validation coverage packages/mcp/test/docs.test.js, packages/mcp/test/stdio-server.test.js, packages/mcp/test/tools.test.js	Tests cover successful retrieval, invalid products, fetch errors, HTTP errors, default instructions, and aggregate tool title registration.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant MCPClient
  participant microlink_docs
  participant docsInputSchema
  participant productDocs
  participant microlink.io
  MCPClient->>microlink_docs: submit product
  microlink_docs->>docsInputSchema: validate product
  docsInputSchema-->>microlink_docs: return validated product
  microlink_docs->>productDocs: load product markdown
  productDocs->>microlink.io: fetch documentation
  microlink.io-->>productDocs: return markdown
  productDocs-->>microlink_docs: return markdown
  microlink_docs-->>MCPClient: return docs output

Loading

Merge Risk: ⚪ Minimal · up to f4f14

The new documentation tool’s validated product catalog and README are consistent, with no identified merge-blocking issue.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 13 files. (2 skipped: 2…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: exposing product documentation through MCP.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 13 files. (2 skipped: 2 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/mcp-product-docs

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[coveralls]

Coverage Report for CI Build 35202926339

Warning

No base build found for commit 4cac14f on master.
Coverage changes can't be calculated without a base build.
If a base build is processing, this comment will update automatically when it completes.

Coverage: 80.79%

Details

• Patch coverage: 67 of 67 lines across 7 files are fully covered (100%).

Uncovered Changes

No uncovered changes found.

Coverage Regressions

Requires a base build to compare against. How to fix this →

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Coverage Stats

Relevant Lines:	5682
Covered Lines:	4611
Line Coverage:	81.15%
Relevant Branches:	955
Covered Branches:	751
Branch Coverage:	78.64%
Branches in Coverage %:	Yes
Coverage Strength:	27.82 hits per line

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💛 - Coveralls