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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds the useful fact that this is a Massive/Polygon.io-backed feed and defines the returned bar fields, but says nothing about rate limits, entitlement requirements, historical depth limits, or pagination behavior beyond the existence of a limit param.

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 with the covered resource stated first, then the payload, then use cases. No filler, though the final sentence is the weakest link given the absence of any parameter guidance.

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 described. However, for an 8-parameter financial-data tool with 5 required params and 0% schema documentation, the description leaves critical inputs (adjusted, sort, limit, date format, multiplier/timespan validity) undocumented, which is not enough for an agent to call it correctly without trial and error.

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% across 8 parameters, so the description carries the full burden and mostly fails. "1 minute through quarterly granularity" loosely gestures at the multiplier/timespan pairing, but adjusted (corporate-action adjustment), sort, limit, and the accepted date format for from/to are never explained, and the multiplier/timespan combination rules — the likeliest source of misuse — remain ambiguous.

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?

Names both a provider lineage (Massive/Polygon.io) and a specific resource: OHLC bars for a US stock ticker, with an explicit granularity span (1 minute through quarterly) and an enumerated return payload (OHLC, volume, VWAP). It is clear what the tool fetches, but never differentiates itself from overlapping siblings like daily_open_close, grouped_daily, or previous_close.

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?

"Use for charting equities, intraday analysis, backtesting historical prices" gives three concrete use cases, so usage is clearly implied. There is no when-not guidance and no routing to the near-duplicate siblings that return similar price data, so an agent must guess between them.

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