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

Annotations already declare readOnlyHint and openWorldHint, and the description adds real context the annotations cannot: a 60 s cache, a $0.010 per-call price, and x402 payment via USDC on Base or Solana. It does not describe what happens on payment failure or when no markets match, which keeps it below a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two dense sentences, front-loaded with the resource and return fields, followed by operational facts. The opening 'Polymarket prediction markets: odds, volume, liquidity' largely restates the title and is mildly redundant, but the remainder earns its space.

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

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

No output schema exists, so the description correctly enumerates the returned fields (probabilities, 24h volume, liquidity, change, end date) and covers cost and caching. The only notable gap is that the default limit and empty-query behavior are not spelled out explicitly.

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

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

Schema coverage is 67%, and the description adds the key semantic for q — 'all words must appear in the question' — which is a much stronger matching rule than the schema's example. The tx payment parameter and the limit bound are left entirely to the schema, so it stops short of full coverage.

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

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

States a specific verb and resource ('Active Polymarket markets matching a query ... with outcome probabilities, 24h volume, liquidity, 24h change and end date') and names the second mode ('or the most traded ones'). No sibling tool covers prediction markets, so the resource alone separates it from market_overview, price, or news.

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

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

Implies usage through the two operating modes: supply a query to match words in the question, or omit it to get most-traded markets. It never explicitly says when to prefer this over market_overview or news_search, and no exclusions or prerequisites beyond payment are stated.

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