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

Annotations already declare readOnlyHint=true, destructiveHint=false and idempotentHint=false, covering the safety profile. The description adds genuinely new behavioral context beyond that: the walk computation triggered by contracts and the note that paper fills take the whole size at one price. It remains silent on pagination, rate limits, or ref/ticker resolution order, so it is useful but not rich.

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?

Three short, front-loaded sentences with no filler; the return format leads and the behavioral caveats follow. The trade-off is that the compressed, jargon-heavy style ('contracts adds walk') costs some readability, keeping it just below the top score.

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?

An output schema exists, so the return value need not be re-explained, and annotations carry the safety profile. What is missing is usage context and how ref and ticker relate for identification, which the description leaves entirely to the schema. Adequate but with clear gaps.

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 the schema already documents all four parameters and the baseline is 3. The description does add meaning for contracts ('walk, that size's cost through the book'), but its phrasing is telegraphic and adds little for ref, depth, or ticker. No compensation is needed since the schema is complete.

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?

Specifies a concrete verb+resource (fetch order book depth) and even the exact return shape: '[price_cents, quantity] bid pairs per side plus best bid and ask'. That is more specific than a generic 'gets the book'. It stops short of naming or contrasting siblings like get_market or get_price_history, so it misses the top of the scale.

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?

There is no explicit when-to-use guidance and no named alternative among the many get_* siblings (get_market, get_price_history, get_cross_venue_quotes). Usage is only implied by the content of the return value. The contracts/walk note hints at a matching use case but never states when to reach for this tool.

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