polymarket-mcp-server

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Close a SIMULATED (paper) bet early

polymarket_paper_close

Close an open paper bet at the current executable bid minus the taker fee, simulating a sale before the market resolves without using real money.

Instructions

Manually close an OPEN paper bet at the current price (models selling before the market resolves). Fills at the executable BID minus the taker fee. No real money.

Args:

id (string): the paper bet id (from polymarket_paper_status).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "id": "<id>"
    },
    "name": "polymarket_paper_close"
  }
}

Input Schema

Name	Required	Description	Default
`id`	Yes	The paper bet id to close (from polymarket_paper_status).
`response_format`	No	Output format: 'markdown' (concise, human-readable; default) or 'json' (full structured data).	markdown

Output Schema

Name	Required	Description	Default
`bet`	Yes
`bankroll`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Sep 28, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Annotations already declare not-read-only, not-idempotent, not-destructive, closed-world. The description adds genuinely non-obvious mechanics: fills at the executable BID minus the taker fee, and that no real money is involved. That pricing/fee disclosure goes beyond the structured fields.

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 action and fill mechanics in two tight sentences, then a short args note. Minor redundancy in repeating the id parameter already covered by the schema, but no wasted prose.

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 need not be explained, and annotations cover the safety profile. The description supplies the fill model and the no-real-money caveat, which is sufficient for a simulated-close tool, though it omits error behavior when the bet is not OPEN.

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 100%, so both id and response_format are documented in the schema itself; the description merely restates the id source. Baseline 3 applies since the schema carries the parameter burden and the description adds no new syntax or format detail.

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 verb (close), resource (OPEN paper bet), and mechanism (at the current price, selling before resolution). It is clearly distinguishable from the sibling paper_open, paper_status, paper_delete, and paper_reset tools.

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?

It implies the precondition that the bet must be OPEN and directs the agent to polymarket_paper_status for the id, which is useful context. However, it never says when to choose this over polymarket_paper_delete or polymarket_paper_reset, leaving the alternative selection to inference.

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