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

Annotations already mark the tool as read-only and idempotent. The description adds valuable behavioral context: data source (live public order books, BTC, six venues), refresh rate (hourly), interpolation method (from published quote depth, never a book walk), and output format. No contradictions with annotations.

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?

The description is two sentences, yet captures purpose, data source, limitations, and output types. Every word adds value, with no redundancy. It is front-loaded with the core action and immediately provides critical caveats.

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?

Given the tool's simplicity (one parameter, no output schema), the description provides complete context: what it does, how it works, limitations, and output summary. It explains the estimation methodology and refresh cycle, leaving no significant gaps for an AI agent to interpret.

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?

The single parameter 'size_usd' has a complete schema description. The tool description adds crucial context about the range of published rungs ($1,000 to $1,000,000) and that the nearest rung is used, which goes beyond the schema. With 100% schema coverage, this extra detail earns a top score.

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?

The description clearly states the tool computes exit cost for a given USD size per venue, using live order books. It names the specific outputs (per-venue cost in bps, cheapest/dearest venue, venue spread) and distinguishes it from sibling tools by focusing on exit cost estimation.

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 description provides clear context for when to use the tool (checking selling costs right now) but does not explicitly mention when not to use it or name alternative tools. It includes important caveats like 'never a book walk' and 'not investment advice'.

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