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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new behavioral facts: this proxies a specific HTTP GET route and costs $0.01 per call. It stops short of stating failure modes or what an unpaid first call returns, which the schema's payment field handles.

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?

Three compact fragments lead with the returned data, then the route, then the price — no wasted words. The telegraphic style is slightly cryptic ('— $0.01') but costs nothing in length.

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 no output schema, the description does list the key returned fields, and the payment mechanics live in the schema. However, it omits units/scale of depth, what 'q' resolves against (topic vs slug), and failure behavior for a small paid lookup tool.

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 both q and payment are fully documented in the schema, including the 402-challenge flow. The description's '?q=' merely restates the query-string binding and adds no format or semantics beyond the schema, so baseline 3 applies.

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 specific resource and its payload precisely: top-of-book bid/ask, spread, and USD depth for a Polymarket book, plus the backing route. It does not distinguish itself from near-siblings such as get_polymarket_odds or find_polymarket_arb, so an agent must infer which one to pick.

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?

There is no statement of when to use this versus get_polymarket_odds, get_polymarket_history, or find_polymarket_arb. The '$0.01' hints that the call is paid, but no guidance on prerequisites or exclusions is given.

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