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Arjein

Polymarket MCP Server

by Arjein

get_price

Retrieve the best available price for an outcome token on a BUY or SELL side, mapping pricing to prediction market outcome probabilities.

Instructions

Fetch the single best available price for a given outcome token on a specified directional side.

Pricing maps intrinsically to outcome probabilities in the range 0.00 to 1.00.

Args: token_id (str): The fundamental token identifier indicating the outcome side. side (str): The designated trading side to check, either strictly 'BUY' or 'SELL'.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
sideYes
token_idYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

B3.4/5.0
Behavior3/5

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses that the returned price maps to an outcome probability in the 0.00–1.00 range and that side must be strictly 'BUY' or 'SELL', but it omits freshness, failure modes, rate limits, and authentication requirements.

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?

The description is front-loaded with the core purpose, then adds a useful semantic note and a structured Args list. It is appropriately sized, with only minor filler in phrasing like 'intrinsically'.

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?

An output schema exists, so return-value details are not required here. Given the simple two-parameter read operation, the description covers purpose, both parameters, the side enum, and the output range well enough to call the tool correctly, though it lacks alternative-tool guidance.

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 description coverage is 0%, so the description must compensate. It documents both parameters and supplies the critical side enum ('BUY' or 'SELL') that the schema leaves as a bare string, though token_id is described somewhat vaguely as a 'fundamental token identifier' without format or examples.

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

Purpose4/5

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

States a specific verb ('Fetch') and resource ('single best available price') and scopes it to an outcome token and directional side. It implicitly distinguishes itself from siblings like get_last_trade_price and get_price_history, but does not name them or explicitly contrast the difference.

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

Usage Guidelines2/5

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

The description implies a use case (current best price for a BUY or SELL side) but gives no explicit when-to-use guidance, no when-not-to-use guidance, and no alternatives such as get_midpoint, get_spread, or get_price_history.

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