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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely new operational context by disclosing the pay-per-call model (x402 USDC on Base) and the error-path behavior — a payment challenge is returned in the response when payment is missing. It stops short of naming the price, rate limits, or refresh cadence, so not a full 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 sentences, no filler: the data scope comes first, the payment/cost constraint second. Every clause earns its place and nothing is repeated from the name or schema.

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-field documentation is unnecessary, and the description covers the non-obvious billing path. The main residual gap is scope — it never says which venues are aggregated or how fresh the quotes are, which matters for a multi-venue price feed.

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 limit and minVolume are already fully documented in the schema, and the description adds no filtering syntax, venue scoping, or default rationale beyond it. Baseline 3 applies when the schema carries parameter meaning.

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?

Names the resource precisely — prediction market prices plus YES+NO deviations — so an agent knows exactly what data comes back, and it is clearly distinct from the other data-feed siblings (funding, tvl, yields). It lacks an explicit verb and does not contrast itself with any sibling, but the domain is unambiguous.

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 states no when-to-use condition, no prerequisites, and no alternatives. Nothing tells an agent when this feed is the right choice over market_pulse, edge, or options, nor whether the call should be avoided when budget or payment is unavailable.

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