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Checking prediction market orderbook

prediction_market_orderbook
Read-only

Live orderbook for a Polymarket market.

When to use:

  • Bid/ask depth, liquidity, and yes-share / no-share order structure.

Key fields:

  • Order Size is share quantity, not USD. Do not describe share size as dollar depth unless you calculate shares × price.

Yes/No price relationship:

  • Yes and No are complementary (Yes + No ≈ $1). A No bid at price $X means willingness to buy No when Yes is near $(1−X).

  • A cluster of No bids at low prices (e.g. $0.20) is resistance for Yes rallying to ~$0.80, NOT a support floor for the current Yes price.

  • When comparing OHLCV odds against orderbook depth, convert No-side prices to Yes-equivalent (1 − No price) before drawing divergence conclusions.

Pitfalls:

  • Do not treat raw no-share prices as bearish yes-share odds — prefer prediction_market_ohlcv for current odds / implied probability.

Prerequisites: If marketId is unknown, call prediction_market_lookup first.

Input Schema

NameRequiredDescriptionDefault
requestYesRequest for a live prediction market orderbook.

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed6 schema fields changed
    • addedInput schema / properties / request / additionalProperties
      Added value: +false
    • removedInput schema / properties / request / anyOf
      Removed value: -[
-  {
-    "additionalProperties": true,
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "description": "Request for a live prediction market orderbook.",
-    "properties": {
-      "marketId": {
-        "description": "Numeric Polymarket market ID (e.g. '654412'). Obtain this from the prediction_market_screener tool.",
-        "maxLength": 100,
-        "minLength": 1,
-        "type": "string"
-      },
-      "page": {
-        "default": 1,
-        "description": "Page number for paginated results.",
-        "minimum": 1,
-        "type": "integer"
-      }
-    },
-    "required": [
-      "marketId"
-    ],
-    "type": "object"
-  }
-]
    • addedInput schema / properties / request / description
      Added value: +"Request for a live prediction market orderbook."
    • addedInput schema / properties / request / properties
      Added value: +{
+  "marketId": {
+    "description": "Numeric Polymarket market ID (e.g. '654412'). Obtain this from the prediction_market_screener tool.",
+    "maxLength": 100,
+    "minLength": 1,
+    "type": "string"
+  },
+  "page": {
+    "default": 1,
+    "description": "Page number for paginated results.",
+    "minimum": 1,
+    "type": "integer"
+  }
+}
    • addedInput schema / properties / request / required
      Added value: +[
+  "marketId"
+]
    • addedInput schema / properties / request / type
      Added value: +"object"
  2. Changed3 schema fields changed
    • removedInput schema / $defs
      Removed value: -{
-  "PredictionMarketOrderbookRequest": {
-    "description": "Request for a live prediction market orderbook.",
-    "properties": {
-      "marketId": {
-        "description": "Numeric Polymarket market ID (e.g. '654412'). Obtain this from the prediction_market_screener tool.",
-        "maxLength": 100,
-        "minLength": 1,
-        "type": "string"
-      },
-      "page": {
-        "default": 1,
-        "description": "Page number for paginated results.",
-        "minimum": 1,
-        "type": "integer"
-      }
-    },
-    "required": [
-      "marketId"
-    ],
-    "type": "object"
-  }
-}
    • addedInput schema / additionalProperties
      Added value: +false
    • changedInput schema / properties / request / anyOf
      Previous value: -[
-  {
-    "additionalProperties": true,
-    "type": "object"
-  },
-  {
-    "$ref": "#/$defs/PredictionMarketOrderbookRequest"
-  }
-]New value: +[
+  {
+    "additionalProperties": true,
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "Request for a live prediction market orderbook.",
+    "properties": {
+      "marketId": {
+        "description": "Numeric Polymarket market ID (e.g. '654412'). Obtain this from the prediction_market_screener tool.",
+        "maxLength": 100,
+        "minLength": 1,
+        "type": "string"
+      },
+      "page": {
+        "default": 1,
+        "description": "Page number for paginated results.",
+        "minimum": 1,
+        "type": "integer"
+      }
+    },
+    "required": [
+      "marketId"
+    ],
+    "type": "object"
+  }
+]
  3. Added

TDQS

A4.8/5.0
Behavior5/5

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

Annotations already declare readOnly/openWorld/non-destructive, yet the description adds substantial domain behavior: units disclosure (share size vs USD), the Yes+No≈$1 complementarity, the trap of reading No bids as Yes support, and the conversion step needed for cross-tool comparison. This is meaningful context beyond the safety profile.

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?

Front-loads the one-line purpose, then sections for when-to-use, key fields, price relationship, pitfalls, and prerequisites. Every block is useful, though the Yes/No pricing explanation runs a few lines longer than strictly needed for tool selection.

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?

With an output schema present, return values need not be described. The description covers when to call, prerequisites, field units, and interpretation pitfalls, leaving no material gap for correct invocation.

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

Parameters4/5

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

Schema coverage is 100% and both query fields (marketId, page) are documented in the schema, so the baseline is 3. The description adds routing value by telling the agent where to obtain marketId (prediction_market_lookup), which goes slightly beyond the schema's own note pointing to the screener.

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 resource and scope: 'Live orderbook for a Polymarket market.' It also implicitly delineates from siblings by naming prediction_market_ohlcv for odds and prediction_market_lookup for ID resolution, so an agent can route without opening schemas.

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

Usage Guidelines5/5

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

Explicit 'When to use' block names the use case (bid/ask depth, liquidity, order structure) and explicitly redirects to prediction_market_ohlcv for implied probability/odds, with a stated prerequisite to call prediction_market_lookup when marketId is unknown. Alternatives and conditions are spelled out.

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

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