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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds useful behavior beyond that by noting only resting orders are returned, ordering is best-first, and the spread is included, but it says nothing about snapshot timing, behavior when requested depth exceeds available levels, or that symbol and pair_id are alternative selectors.

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?

One tight sentence carries scope, ordering, and the spread, followed by a short usage cue. Nothing is redundant and the most important information is front-loaded.

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?

For a simple read-only lookup with rich annotations, a full output schema, and fully described parameters, the description covers what is needed to call it. The only gap is the unstated mutual exclusivity of symbol and pair_id and any note on truncated depth.

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 depth (1-100, default 20), symbol format, and pair_id are fully documented in the schema. The description adds no meaning beyond that, so the baseline of 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 concrete resource and scope: resting bids and asks for one market, ordered best-first, including the spread. That is specific enough to separate it from get_trades or get_order by resource noun, though no sibling is named explicitly for contrast.

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 quoted question '"How deep is the BTC book?"' implies the use case (checking liquidity/depth) but there is no explicit when-to-use vs. when-not guidance and no alternative tool is named for related needs such as single-order lookup or recent trades.

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