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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable behavioral context: keyless access, contract prices as implied probabilities, return of compact markets with up to 8 contracts. No contradictions with annotations.

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 sentences, front-loaded with key details (what it lists, domain, size, keyless, return structure). Every sentence provides essential information with no wasted words. Ideal conciseness for agent parsing.

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?

Given no output schema, the description explains return content (compact markets, up to 8 contracts, implied probabilities). It also mentions market count and authentication requirement. The description is nearly complete but could benefit from noting that results are not paginated (limit handles it).

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% with clear descriptions for both params (limit, open_only). The description adds overall context about market count and contract count but does not enhance parameter-specific meaning. Baseline 3 is appropriate as schema carries the burden.

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?

The description clearly states it lists active PredictIt prediction markets with specific details (real-money, US-politics-focused, ~250 markets, contract prices as probabilities, keyless, returns compact markets with up to 8 contracts). It distinguishes the tool's purpose from siblings like get_market or search_markets, though not explicitly. The verb 'list' and resource 'markets' are specific and well-defined.

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?

The description implies usage for viewing active markets and mentions it is keyless, but does not explicitly state when to use vs. alternatives (e.g., search_markets for filtering). It provides context (always returns active markets) but lacks exclusions or when-not-to-use guidance.

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