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

Annotations already cover the read-only safety profile (readOnlyHint true, destructiveHint false), so the burden is lower. The description adds real behavioral context beyond that: OBV is anchored at 0 on the first bar of the range, absolute values shift with startDate, and values are not comparable across calls. This is a non-obvious trait an agent would otherwise get wrong.

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 sentences, front-loaded with the definition, then usage, then the critical anchoring caveat. Every sentence earns its place and the most decision-relevant warning (don't compare levels across calls) is clearly stated.

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 and a read-only, non-destructive profile covered by annotations, the description supplies what matters: what OBV is, how it is computed, and how startDate distorts absolute levels. It does not enumerate returned fields, but for a self-describing indicator series that is a minor omission.

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%, so the baseline is 3, but the description adds genuine meaning about startDate that the schema does not: it explains that the range start shifts the anchor and therefore the absolute level. That is added semantic value beyond the schema's format/default note.

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 ('On-Balance Volume (OBV) for a stock') and even defines the computation (adds volume on up-closes, subtracts on down-closes, flat on equal closes). Among siblings like GetAverageTrueRange, GetBollingerBands and GetStochasticOscillator, an agent can tell immediately this returns a volume-flow indicator.

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?

'Useful for confirming or diverging from price trends with volume flow' gives an implied analytical use-case but no explicit when-to-use/when-not and no named alternative among the many indicator siblings. Adequate minimum-viable guidance, not routing.

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