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

Goes well beyond the readOnly/idempotent annotations by defining sort order (bids highest first, asks lowest first), the [price, quantity] shape, pending_* as matched-but-unsettled orders, the presence of the last settled order, and both ts and recorded_ts in epoch ms. It also discloses the coverage limit and the error condition, which annotations cannot express.

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?

A single dense sentence that leads with what the tool returns and then unpacks field semantics in a readable order. It is information-rich without padding, though the parenthetical pile-up (`pending_*`, ts definitions) makes it slightly harder to scan than a two-sentence split would be.

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 carries the return-value burden and does so completely: it names the fields, their ordering, their units, and the error/coverage boundary. For a single-parameter read tool this leaves nothing an agent needs unresolved before calling.

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?

Only one parameter and the schema already documents it at 100% coverage, including that it comes from predictfun_markets and is required. The description reinforces that the call targets exactly one market but adds no format or validation detail 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 a specific resource and view: the newest recorded order book of one Predict.fun market, priced on the first outcome (Yes). That is clearly distinct from siblings like predictfun_market_detail or predictfun_market_trades, though the description never explicitly names an alternative to contrast against.

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?

Gives concrete eligibility context: books exist for the ~1,000 most active open markets, and no record within 30 days is an error, which tells an agent when this call will fail. It stops short of explicit routing such as 'for trade history use predictfun_market_trades instead'.

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