polymarket-trader-mcp

markets.watch_price

Subscribe to a market token ID to stream live price updates, unsubscribe to stop, or check WebSocket connection status.

Instructions

Manage live WebSocket price subscriptions for real-time market updates. Subscribe to a token_id to start streaming price changes, unsubscribe to stop, or check connection status.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "markets.watch_price"
  }
}

Input Schema

Name	Required	Description	Default
`action`	No	subscribe=start streaming, unsubscribe=stop streaming, status=show connection info	status
`token_id`	No	Market token ID to subscribe/unsubscribe. Required for subscribe/unsubscribe, omit for status

Schema Changelog

Changes observed during successful MCP inspections.

AddedApr 30, 2026

TDQS

A4/5.0

Behavior3/5

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

With no annotations, the description must convey behavior. It discloses the three actions and their effects (start streaming, stop, check status). However, it lacks details on connection management, error handling, or how updates are delivered after subscribing, leaving some behavioral aspects implicit.

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 description is extremely concise: two sentences that front-load the purpose and enumerate actions. Every sentence adds value without redundancy.

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?

For a simple two-parameter tool with no output schema, the description covers the core actions and parameter conditions. It could mention the WebSocket update channel after subscribing, but given the low complexity, it is nearly complete.

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 coverage is 100%, and the schema descriptions already clarify the enum values and token_id requirement. The tool description adds no new parameter information beyond what is in the schema, so it does not increase semantic value.

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?

The description clearly identifies the tool's purpose: managing live WebSocket price subscriptions. It specifies the resource (price updates) and the actions (subscribe, unsubscribe, status), making it easily distinguishable from siblings like 'markets.price' (single fetch) and 'markets.watch' (watchlist).

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?

The description states the context for using the tool ('real-time market updates') and the three actions. While it does not explicitly mention when not to use or compare with alternatives, the context is clear enough for an agent to decide.

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