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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds value beyond them: a 20-ticker result cap, a note that free-account data delays apply, and a disclaimer that the output is descriptive rather than advisory. It does not describe pagination or session-boundary behavior, but the added context is substantive.

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 sentences, front-loaded with scope and the ticker cap before the operational and compliance notes. The 'not a recommendation' disclaimer earns its place as a compliance constraint, though it could be trimmed slightly.

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 return values need not be explained. Combined with the date-omission rule, result cap, and data-delay caveat, an agent has enough to invoke it correctly; only sibling differentiation is missing.

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 0%, so the description must carry the burden, and it does explain the meaning of the nullable date default ('omit date for the latest visible session'). It does not state the accepted date format or range, which the schema only implies via format: date.

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 ('Get unusual option activity') plus the aggregation shape ('grouped by symbol') and a hard cap ('up to 20 tickers'). It is distinguishable from get_option_activity by the 'unusual' qualifier, but it never names that sibling or clarifies how the two differ.

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?

'Omit date for the latest visible session' is a concrete operational rule for the single optional parameter. However, there is no guidance on when to prefer this over get_option_activity, get_options_structure, or list_option_activity_dates, and no stated exclusions or preconditions.

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