Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/masonchow/source-map-parser-mcp/copilot-instructionsgit clone --depth 1 https://github.com/MasonChow/source-map-parser-mcpWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.01243 | $0.01243 |
| Opus 5 | $0.00622 | $0.00622 |
| Sonnet 5 | $0.00249 | $0.00249 |
| Haiku 4.5 | $0.00124 | $0.00124 |
Grade A, and why
source-map-parser-mcp copilot-instructions.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Source Map Parser MCP Server
Always reference these instructions first and fallback to search or bash commands only when you encounter unexpected information that does not match the info here.
This is a TypeScript MCP (Model Context Protocol) server for parsing JavaScript source maps. It provides tools to map minified JavaScript error stack traces back to their original source code locations.
Working Effectively
Bootstrap and Build (REQUIRED)
- ALWAYS run these commands in order to get started:
npm install-- takes ~1 second. Dependencies are already cached.npm run build-- takes ~4-5 seconds total. NEVER CANCEL. Set timeout to 30+ seconds.- The build process includes:
npm run build:vite(Vite build ~1.3 seconds)npx -y repomix(documentation generation ~3 seconds)
Testing
npm run test:ci-- takes ~11 seconds total. NEVER CANCEL. Set timeout to 30+ seconds.- Memory cache tests: 8 tests pass in <1 second
- Client test: Currently times out after 10 seconds (known issue - integration test configuration)
- Note: The client test timeout does NOT indicate the server is broken - it's a test configuration issue
- Do NOT attempt to fix the client test timeout unless specifically asked - it's not critical to functionality
Running the Server
- Method 1 (Development):
npx tsx src/main.ts - Method 2 (Built):
node dist/main.es.js - Method 3 (NPX):
npx -y source-map-parser-mcp@latest - The server runs as an MCP stdio server and will wait for MCP client connections
Environment Configuration
SOURCE_MAP_PARSER_RESOURCE_CACHE_MAX_SIZE- Max memory cache (default: 200MB)SOURCE_MAP_PARSER_CONTEXT_OFFSET_LINE- Context lines around errors (default: 1)
Validation
ALWAYS Test These Scenarios After Changes:
- Build Validation:
npm run buildmust complete successfully- Check that
dist/main.es.jsanddist/main.cjs.jsare created - Verify no TypeScript compilation errors
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 130 lines · 1,243 tokens per session scan A 5577a46588e6
source-map-parser-mcp copilot-instructions.md is an instructions file published in the GitHub repository MasonChow/source-map-parser-mcp (2 stars, last pushed 11mo ago), licensed MIT. It adds 1,243 tokens to every session, about $0.0062 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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