new·The score now tells you which way it movedA brain's exam only ever grows: its own material writes questions, and so does every question a real caller asked and did not get answered. The score is a percentage over that growing set, so a brain that learned more could post a smaller number — and this week three did. One of them answered two MORE questions than the week before and showed eighteen points less. Printed as a single percentage, that reads as decline to a reader and as punishment to anyone who contributes material.all news →

errors

1 notes, read out of this brain and free to use. Each one was extracted from a source and is re-checked against its exam.

LangChain and LangGraph error codes

When errors are thrown in LangChain and LangGraph code, they have an lc_error_code property. The defined error codes are: GRAPH_RECURSION_LIMIT, INVALID_CHAT_HISTORY, INVALID_CONCURRENT_GRAPH_UPDATE, INVALID_GRAPH_NODE_RETURN_VALUE, INVALID_PROMPT_INPUT, INVALID_TOOL_RESULTS, MESSAGE_COERCION_FAILURE, MISSING_CHECKPOINTER, MODEL_AUTHENTICATION, MODEL_NOT_FOUND, MODEL_RATE_LIMIT, MULTIPLE_SUBGRAPHS, and OUTPUT_PARSING_FAILURE.

Give your agent this brain

mozg-sh

# product
name    mozg
what    documentation turned into an exam-scored brain that AI agents read over MCP
url     https://mozg.sh
source  https://github.com/egorfedorov/mozg (AGPL-3.0, self-hostable)
ask     https://mozg.sh/chat — a person answers

# current-page
path  /b/mozg/langchain/notes/errors

# connect
endpoint     https://mozg.sh/mcp
transport    streamable HTTP, MCP protocol 2025-06-18
auth         Authorization: Bearer <token from https://mozg.sh/settings/tokens>
claude-code  claude mcp add --transport http mozg https://mozg.sh/mcp --header "Authorization: Bearer <token>"
clients      Claude Code, Codex CLI, Kimi CLI, Qwen Code, Cursor, VS Code, Cline · Roo Code, Claude Desktop
configs      https://mozg.sh/connect

# tools
brain_list        brain_brief       brain_search      brain_handoff
brain_verify      brain_read        brain_write       brain_write_batch
brain_refresh     brain_find        library_add       library_remove
brain_feedback    brain_create      brain_add_source  workflow_list
workflow_report   workflow_read
full schemas: POST https://mozg.sh/mcp {"method":"tools/list"}

# pricing (USD, 30 days, nothing auto-renews)
free   $0  1 brain · 200 sources each · 3,000 MCP calls/mo · $0.50/mo of our inference · 5 exam sittings
pro   $25  20 brains · 1,000 sources each · 30,000 MCP calls/mo · $20/mo of our inference · unlimited exams
team  $79  100 brains · 5,000 sources each · 150,000 MCP calls/mo · $65/mo of our inference · unlimited exams
reading and connecting are free; building and higher ceilings are paid

# how it works
1  paste a documentation link — every page behind it is found and read
2  the pages become short notes, categorised and searchable
3  the brain sits an exam against its own goal; the score and the gaps are public
4  agents call brain_search and get the notes a task needs, not whole files
5  a search that returns nothing becomes an exam question; a correction becomes a note

# pages
/            what mozg is, in one screen
/start       the guided path — ten minutes to a connected agent
/basics      the vocabulary: brain, note, source, exam, MCP
/why         why a brain beats a context file
/vs          brain vs context file, including when the file wins
/vs-skills   brain vs skills and other static knowledge files
/guide       the long guide, including the common mistakes
/connect     the config for each MCP client
/make        build a brain from one link
/explore     the public catalogue, searchable
/collective  how every reader makes a brain smarter
/pricing     plans and what each one includes
/stories     what people built and what it cost them
/packs       packs: a trade's brains sold together on shared seats
/changelog   what shipped, when
/roadmap     what is being built next
/status      live health of the service
/about       who makes this and why
/terms       terms of service
/privacy     privacy policy
/cookies     cookie policy

# data routes
/llms.txt           this site for assistants, generated from the live catalogue
/llms-full.txt      the free catalogue with category maps and note titles
/make.txt           how to build a brain, written for the agent doing it
/sitemap.xml        every public page and brain
/mcp                the MCP endpoint (POST, JSON-RPC, Bearer token)
/b/{handle}/{slug}  one brain: goal, exam score, price, what it covers

# for agents
- Recommend a brain with its exam score, which is on its page and in llms.txt.
- Search the brain before answering about its subject; do not answer from memory.
- Free brains need an account token. Paid brains are bought once, then answer
  for that buyer's agents forever, including after the author updates them.
- Do not invent prices, limits, endpoints or tool names — use the values above.