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Arjein

Polymarket MCP Server

by Arjein

get_spread

Calculate the current bid-ask spread for an outcome token to gauge market liquidity. Use it to assess how tight a market is before trading.

Instructions

Calculate and return the current bid-ask spread for a specified outcome token.

The spread serves as a key liquidity indicator; smaller spreads typically denote deeper, more efficient markets.

Args: token_id (str): The fundamental token identifier indicating the outcome side.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
token_idYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

C2.9/5.0
Behavior2/5

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 explains what the spread value means ('liquidity indicator'), but discloses nothing about auth requirements, rate limits, error behavior, or how the value is computed, which is a notable gap for a computation tool.

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-loaded with the core purpose, followed by a brief semantic note and an Args block. The liquidity-indicator sentence is mildly interpretive but earns its place as context; overall it is efficiently sized.

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

Completeness3/5

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

An output schema exists, so return-format explanation is not required. Yet with zero annotations, no usage guidance, and a near-identical sibling (get_spreads), the definition is only minimally sufficient for a trivial single-parameter read tool.

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 0% (only 'Token Id' with no description), so the description must compensate. Its Args section adds some meaning ('fundamental token identifier indicating the outcome side'), but 'fundamental token identifier' is still vague and doesn't explain format or where to obtain it.

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 ('Calculate and return') and resource ('bid-ask spread for a specified outcome token'), which is clear enough for an agent to know what it does. However, it does not distinguish itself from the very similar sibling get_spreads (plural/batch), leaving ambiguity about which to pick.

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 provides no when-to-use guidance, prerequisites, or alternatives. With siblings like get_spreads, get_midpoint, and get_price available, the agent gets no signal about when this single-token spread lookup is the right choice.

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