Buy shares

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

Annotations already declare the mutation/safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the bar is lower. The description adds real value beyond them: immediate fill against the live order book, fee recording, simulated/no-real-order semantics, and that Kalshi fees follow the series fee schedule. It does not mention slippage expectations or auth requirements, so not 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?

Front-loaded with purpose and scope, then behavior, then alternatives. Four tight sentences with no filler; every clause adds routing or behavioral 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?

With an output schema present, return values need not be explained, and the description covers the remaining burden: what the fill does, that it is simulated, fee handling, and sibling routing. Nothing an agent needs 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?

Schema coverage is 100%, so the schema already documents slug_or_id (including the 'kalshi:<TICKER>' format), outcome, amount_usd, order_type, and account. The description adds only light framing ('paper money', fee schedule) that overlaps with existing schema text, so the 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 (Buy) plus resource (shares of a Polymarket or Kalshi outcome) and scope (paper money). It explicitly distinguishes itself from siblings by naming place_limit_order and sell, so an agent can route without opening schemas.

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 gives when-to-use: immediate fill against the live order book. It names the alternative (place_limit_order for a resting order at your price) and the exit path (sell), covering both the primary and the exclusionary cases.

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