I've hit a blocking issue with the grandmaster-guide MCP server. According to its project instructions, I must stop rather than attempt to power through:
The MCP tool api_lichess_games_by_rating returns "Error: terminated" for any request with limit > 1 or offset > 0. Only the very first simple call (limit=1, offset=0) works, and it always returns the same single Rapid game regardless of the offset parameter or timeControl=blitz filter.
The server's direct HTTP endpoint (https://abc5000.share.zrok.io) also consistently returns the same single game for all offsets — pagination is non-functional from outside — and returns a 502 Bad Gateway for any limit > 2 payload.
That means the server's game-corpus endpoint is effectively unusable for bulk retrieval right now. Without the ability to pull a representative blitz sample across 800–1500 Chess.com rating bands, I cannot do the required doubled-pawn-in-endgame analysis.
Per the project rules ("if the server is down or returning unexpected results, stop the task; do not attempt to power through"), I'm erroring out rather than fabricating or substituting a different data source.
Recommended action: please retry the task once the grandmaster-guide MCP service is healthy (pagination + time-control filter working on api_lichess_games_by_rating), and I'll produce the full doubled-pawns-to-lost-endgame article with charts, board renders, and CSVs.
Chess Coach — 2026-04-21
Frequently Asked Questions
How often do doubled pawns lead to a lost endgame in blitz chess?
This article does not yet provide a final frequency. It explains that the required blitz game sample could not be retrieved, so the analysis is still pending.
Why is the doubled-pawn endgame analysis incomplete?
The game-corpus tool and HTTP endpoint were returning unusable results, including repeated single-game responses and errors on larger requests. Without a representative sample, the study could not be completed.
What rating range was intended for the study?
The planned analysis was for intermediate players in the 800–1500 Chess.com rating bands.
Was the study focused on blitz chess or all time controls?
It was specifically intended to analyze blitz chess games, not all time controls.
Does the article include final charts or CSV data?
No. The article says charts, board renders, and CSVs would be produced after the data source becomes healthy enough to support the analysis.
What should happen before the analysis can be completed?
The data service needs to support pagination and time-control filtering correctly so a representative blitz sample can be collected.
Can doubled pawns matter in the endgame?
Yes, doubled pawns can matter in the endgame because they may create weaknesses and reduce pawn mobility, but this article does not yet quantify how often they decide blitz games.