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

With no annotations available, the description carries the full burden and exceeds it: it reveals the ~60s warehouse capture source, row structure, required date parameters, max 7-day window with 422 error, coverage start date, and 5-min cache. This is rich behavioral context beyond what annotations would typically provide.

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 packs purpose, usage guidance, output schema, constraints, and caching into one dense but well-structured paragraph. Every sentence adds value, and the information is front-loaded with the most important details first.

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?

Despite 7 parameters, no output schema, and no annotations, the description is highly complete: it covers input requirements (ticker, date range), output structure (rows + window summary), error behavior (422 for >7 days), data availability start, and caching. It is fully self-sufficient for an agent to select and invoke correctly.

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 only 14% (only ticker described), so the description must compensate. It does so by explaining the critical 'date OR start(+end)' requirement, the 7-day max window, and the meaning of output fields (polarity, premium_total, window summary). It does not detail side/limit/min_premium, but those are partially self-evident from enums and names.

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 identifies the tool as 'Historical options-flow aggregates for one ticker' and explicitly contrasts it with 'the live /intel/options_flow tool' for current snapshots. This distinguishes it from sibling options_flow tools and provides a specific verb+resource+scope.

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 explicitly states 'Call when you need how flow EVOLVED' with a concrete example ('was NVDA flow bullish before the earnings pop?'), and clarifies it is for historical evolution rather than the current snapshot. It also notes the required date/start+end parameters, giving clear when-to-use guidance.

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