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

Annotations only cover readOnlyHint and openWorldHint, yet the description adds substantial undisclosed behavior: per-call cost ($0.003 USDC), the x402 payment rails (Base, Solana, Arc), that failed calls are not charged, venue alternation in results, and the 50-row cap. This is exactly the value-added over structured fields the dimension rewards.

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?

Dense but front-loaded: purpose, result shape, ordering/limit, then cost and disclaimer. Each sentence carries information an agent needs, with no restatement of the title or filler.

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-value explanation is not strictly required, yet the description still sketches row fields, and it fully covers the non-obvious cost/payment model. 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 description coverage is 100%, so the schema already documents all six parameters, making 3 the baseline. The description adds only marginal semantics beyond that, clarifying volume units per venue and result alternation, but not filter syntax or precedence.

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 (Searches) and resource (open prediction markets) plus the two venues and the filter dimensions. The word 'open' implicitly separates it from resolved-market siblings like pm_resolved, but no sibling is named, so an agent must infer the boundary itself.

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?

Usage is implied: keyword search with optional closing-date window and minimum volume. There is no explicit when-to-use / when-not-to-use guidance and no routing to the many pm_* and markets_* siblings, so the agent gets context but not disambiguation.

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