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

Far exceeds what the annotations provide. Documents side semantics (buy walks asks, sell walks bids), that impact is always a positive cost number from the book's own mid, the edge cases where vwap/impact are null (book insufficient vs ~0 notional), and the capacity_is_lower_bound caveat when the whole supplied book is consumed.

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?

Front-loads the core purpose in the first clause and then qualifies behavior. Some sentences are dense and the return-value enumeration is long, but every statement earns its place and no filler is present.

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 contract fully, including the null conditions, book_sufficient flag, and capacity_is_lower_bound semantics. An agent has everything needed to call and interpret this 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 the baseline is 3, but the description meaningfully enriches it: it explains side semantics, the either/or relationship between notional_usd and impact_budget_bps, and the return fields correlated with each parameter mode. It stops short of describing the [price, size_base] level format, which the schema handles.

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 and resource ('walk the book' impact/capacity) and precisely describes the two computational modes. The description would let an agent distinguish it from siblings like run_swap_price_impact without opening the 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 explicit trigger phrases ('what's my price impact if I trade $X', 'how much can I trade before impact exceeds Y bps') that map cleanly to the two modes. No explicit when-not or named alternative, but the usage context is very clear.

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