BetterChess

Analyse a chess position

chess_analyse

Read-only

Returns an engine evaluation of a chess position: the strongest candidate moves with their scores, and the position's checkable facts — side to move, whether that side is in check, undefended pieces and the pieces attacking them, and the material balance. Accepts a FEN, a PGN, or a list of SAN moves from the starting position. Also reports what the OPPONENT would play if it were their turn, which is the difference between a position being quiet and merely looking quiet. Pass considering with a move you are thinking of playing and it returns what that move actually walks into — a losing move is usually not in the top candidates, so asking about it directly is the only way to find out.

Input Schema

TableJSON Schema

Name	Required	Description
`fen`	No	FEN of the position.
`pgn`	No	PGN; the position after the final move is used.
`moves`	No	SAN moves from the start, e.g. ["e4","e5"].
`traps`	No	Also scan the captures and checks available to the side to move and return the ones that lose, each with its refutation. Slower — several extra searches.
`multipv`	No	How many candidate moves (1-5, default 3).
`considering`	No	A move you are thinking of playing, in SAN, e.g. "Ng5". Returns the evaluation after it and the line that refutes it.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

Changed1 schema field changedSep 2, 2026

addedInput schema / properties / traps

Added value: +{
+  "description": "Also scan the captures and checks available to the side to move and return the ones that lose, each with its refutation. Slower — several extra searches.",
+  "type": "boolean"
+}

Changed1 schema field changedSep 2, 2026

addedInput schema / properties / considering

Added value: +{
+  "description": "A move you are thinking of playing, in SAN, e.g. \"Ng5\". Returns the evaluation after it and the line that refutes it.",
+  "type": "string"
+}

First observedSep 1, 2026

TDQS

A4.5/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, so safety is covered. The description adds valuable behavioral context: it explains that the tool reports what the opponent would play (distinguishing quiet positions), explicitly warns that the 'traps' parameter is slower due to extra searches, and clarifies that a losing move may not appear in top candidates, requiring the 'considering' parameter. This goes well beyond what annotations provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact yet rich: the first sentence conveys primary functionality, the second covers input formats, the third introduces a key nuanced behavior, and the fourth explains the 'considering' parameter. Every sentence adds value with no redundancy, and critical details are front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite lacking an output schema, the description fully specifies what the tool returns (candidate moves, scores, checkable facts, opponent's response, refutation lines for 'considering'). It also covers all input formats, optional parameters, and performance trade-offs, leaving no critical gap for an agent to call it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all six parameters already have descriptive text in the schema. The description itself only elaborates on 'considering' and 'traps' behavior, but the schema already covers the rest. Per the baseline rule for high coverage, a score of 3 is appropriate because the description adds minimal extra beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Returns an engine evaluation'), a clear resource (a chess position), and enumerates the concrete outputs (candidate moves, scores, checkable facts). It distinguishes itself from siblings by focusing on engine evaluation and opponent responses, making its purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear usage context, such as using the 'considering' parameter to evaluate a specific move when it might not appear in top candidates, and explains that 'traps' adds slower scans. However, it does not explicitly mention when not to use this tool or compare it with sibling tools like chess_review or chess_rig, so it lacks explicit exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All BetterChess tools Inspect

Try in Browser

RayrunBuild, deploy, and operate MCP servers without becoming an infrastructure team.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

TDQS

A4.3/5.0

Disambiguation5/5

Each tool targets a distinct aspect of chess analysis: position evaluation, attack squares, game review, and browser rig generation. No two tools overlap in purpose, so an agent can easily select the correct one.

Naming Consistency4/5

All tools share the 'chess_' prefix and follow a verb-like second word (analyse, review, rig), except 'attacks' reads as a noun rather than an action. This minor deviation is easily readable and the pattern is otherwise consistent.

Tool Count4/5

With only 4 tools, the server feels compact but not under-scoped. The tools cover essential chess analysis tasks, and each one earns its place, though a few more could round out the surface.

Completeness4/5

The server covers analysis, tactical awareness, full game review, and even a browser integration rig. Missing common features like move validation or opening lookup, but the core workflows are well-supported for its apparent purpose.

Resources

Need Help?