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Arjein

Polymarket MCP Server

by Arjein

get_midpoints

Calculate mid-market prices concurrently for multiple Polymarket outcome tokens using comma-separated token IDs.

Instructions

Calculate and return the mid-market prices concurrently for multiple outcome tokens.

Args: token_ids (str): A comma-separated list of foundational token IDs to fetch fair value for.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
token_idsYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.0.0

TDQS

A3.9/5.0
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 prices are calculated concurrently, but it does not state read-only safety, authentication needs, rate limits, or error behavior; the output schema helps only with return shape.

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 purpose sentence is front-loaded and the Args block is compact and directly useful. There is no redundant or wasted text.

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?

With an output schema present, return values do not need explanation. The description covers the single parameter and the operation clearly enough for a simple getter, though it omits explicit routing guidance versus the singular get_midpoint.

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

Parameters5/5

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

Schema description coverage is 0% and the schema only says token_ids is a string. The description fully compensates by explaining that token_ids is a comma-separated list of foundational token IDs used to fetch fair value.

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?

The description uses a specific verb and resource: calculate and return mid-market prices. It also scopes the operation to multiple outcome tokens, which implicitly separates it from the singular get_midpoint sibling, though it does not name that sibling explicitly.

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

Usage Guidelines3/5

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

The phrase 'for multiple outcome tokens' implies when this batch tool should be used instead of a single-token alternative, but no explicit when/when-not guidance or named alternative is provided. Usage is therefore implied rather than stated.

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