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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds substantive value by enumerating the return contents (depth ladder with size at every visible level, OHL/last, shares/notional traded, OI), but says nothing about freshness, rate limits, or snapshot timing.

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 what is returned before the when-to-use guidance. Every clause earns its place, including the parenthetical field enumerations that serve as the return-value spec.

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?

There is no output schema, but the description compensates by specifying both the book shape and the session stats fields an agent would receive. Combined with the annotations covering safety, nothing needed to call or interpret this tool 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 coverage is 100% and the single slug parameter is already documented in the schema, including its source (polymarket_us_search). The description only repeats that provenance, adding no new syntax or format details, so the 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?

States a specific verb+resource+scope: a full order book plus session stats for one Polymarket US market by slug. It explicitly distinguishes itself from polymarket_us_bbo, so an agent can tell the two apart without opening a schema.

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 the trigger ('check actual tradable depth before sizing a trade'), names the alternative and how it differs ('polymarket_us_bbo gives only the top of book'), and tells the agent where the slug comes from (polymarket_us_search). Nothing is left to inference.

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