polymarket-mcp-server

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Snapshot markets for calibration

polymarket_calibration_snapshot

Record current implied probabilities of open Polymarket markets to a local file, enabling later calibration checks on whether markets resolve as predicted.

Instructions

Record a SNAPSHOT of current open markets' implied probabilities (one per outcome) into a local file, so that when they resolve, polymarket_calibration_report can measure whether the market is well-calibrated (do 30% markets resolve Yes ~30% of the time?). Forward-only. Writes a local file; no real money.

Args:

query (string, optional): snapshot markets about a keyword; omit for top markets by volume.
limit (1-50, default 25), min_volume (default 0, filters dead markets).

Returns: { recorded, skipped, totalSnapshots, byBucket }. Re-running the same day won't double-count.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`limit`	No	Max markets to snapshot (default 25).
`query`	No	Keyword to snapshot markets about; omit for top markets by volume.
`min_volume`	No	Skip markets below this total volume (filters dead markets).
`response_format`	No	Output format: 'markdown' (concise, human-readable; default) or 'json' (full structured data).	markdown

Output Schema

TableJSON Schema

Name	Required	Description	Default
`skipped`	Yes
`byBucket`	Yes
`recorded`	Yes
`totalSnapshots`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 28, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations already flag readOnlyHint=false and destructiveHint=false; the description adds real value by clarifying 'Writes a local file; no real money,' the forward-only nature, and the dedupe behavior 'Re-running the same day won't double-count.' Note this dedupe claim sits in mild tension with idempotentHint=false, though it is scoped to same-day re-runs rather than a flat contradiction.

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

Conciseness4/5

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

Purpose is front-loaded, followed by a compact args list and a returns line. Dense but well-organized; the parenthetical calibration explanation earns its place by clarifying intent.

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

Completeness4/5

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

Covers purpose, usage, args, return shape, idempotency, and the downstream report relationship. Since an output schema exists, return values need not be re-explained, and the description is nearly complete for correct invocation.

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 the schema already documents all parameters. The description restates query/limit/min_volume with light usage color ('filters dead markets', 'omit for top markets by volume') but omits response_format, adding only marginal meaning 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?

States a specific verb and resource: 'Record a SNAPSHOT of current open markets' implied probabilities ... into a local file.' It also explicitly distinguishes itself from the sibling it feeds, polymarket_calibration_report, so an agent understands the relationship without opening either schema.

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?

Provides clear when-to-use context: snapshot now so the later report can measure calibration, and the key constraint 'Forward-only.' It names the downstream tool but does not give explicit when-not-to-use guidance or alternatives for capturing market state.

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