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

Annotations already cover the safety profile (readOnlyHint, idempotent, openWorld). The description adds the default-latest behavior, which is useful, but says nothing about return shape, pagination, or what 'Pro.' entails. With annotations carrying the burden, a 3 is appropriate.

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 resource and scope well, but the malformed fragment 'Pro.' at the end is unclear and wastes a closing beat. Otherwise efficient, though the example query adds little.

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 single-parameter, annotation-covered read tool this is close to adequate, but the undefined 'Pro.' token and absence of any note on the two output sections leave small gaps. Enough to call correctly, not rich.

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 date parameter is fully documented with format and default. The description repeats the default-latest behavior but adds no syntax or edge-case detail beyond the schema, so baseline 3 is correct.

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: off-exchange (dark pool) activity with two distinct outputs — a market-wide share and a per-ticker notional ranking. An agent can distinguish it from siblings like market_tide or abnormal_trades_current 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?

Provides an explicit usage quote ('where is dark pool activity concentrated?'), which gives clear context for when to reach for this tool. It does not name an alternative or state exclusions, so it falls short of a 5.

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