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

Annotations already declare readOnlyHint and openWorldHint, so safety and network reach are covered. The description adds genuinely useful behavior beyond them: the returned market is 'conservatively matched', warning that the match may be approximate, and that source links accompany the result. It does not mention freshness/latency or rate limits, which keeps it short of 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?

The core action and its return shape lead the description, followed by the disambiguation sentences. Four short sentences with almost no filler, though the trailing voxodds.com URL is closer to product promotion than call-critical information.

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?

An output schema exists, so return values need not be spelled out, and the single required parameter is fully documented in the schema. The description supplies the one thing structure cannot: that matching is conservative and that executable pricing requires a different tool. Nothing needed to call this correctly is missing.

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?

There is a single parameter with 100% schema description coverage and an inline example ('Will the Fed cut rates in December?'), so the schema carries the semantics. The description only reinforces that the question is natural-language and about a future event, adding no format, length, or ambiguity guidance (e.g., how to phrase multi-outcome questions). Baseline 3 is appropriate.

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 ('Get current Polymarket probabilities') plus the input shape ('natural-language event question'), so the agent knows exactly what is produced. It distinguishes itself from the executable-quote siblings (list_executable_opportunities, get_executable_quote) and from the Kalshi comparison surface, which no other sibling provides.

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?

Explicitly routes the agent: use this for indicative Polymarket probabilities, and switch to list_executable_opportunities or get_executable_quote when an executable quote is needed. It also flags where the Kalshi comparison lives, giving a when-not boundary rather than leaving the agent to guess among 17 siblings.

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