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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: real-time bars for watchlisted symbols versus 15-minute delay otherwise, plus a 'Pro' tier gate. No rate-limit or error behavior is disclosed.

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?

A single dense sentence front-loads the resource and scope, then adds latency and tier caveats. Every clause carries information; nothing is padding.

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?

With no output schema, the description still conveys the return shape ('OHLCV bars', 'most recent limit bars') and the delay behavior. It stops short of explaining the response envelope (e.g. timestamps, ordering, pagination beyond limit), which is the only remaining gap for a 4-param tool.

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% and every parameter's purpose, range, and default is documented in the schema. The description largely restates those facts ('1 to 60 minute bars', 'default today', 'most recent limit bars') rather than adding syntax or format detail, so baseline 3 applies.

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: 'Intraday OHLCV bars for a stock on a session'. An agent immediately understands this returns candle data, not quotes or indicators. It does not explicitly contrast with close siblings like stock_quote or technical_indicator, so it stops short of a 5.

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?

Usage is only implied by the description's scope ('intraday', '1 to 60 minute bars', 'Pro' tier). There is no explicit when-to-use, no when-not, and no named alternative, but the intraday framing does help an agent place it relative to quote/indicator tools.

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