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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds meaningful behavior beyond that: it explains the response is 'render-ready' for the widget, and that the client feeds each `series` entry unchanged. This gives the agent useful context about output consumption without contradicting annotations.

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 is properly structured with a clear intro, parameter breakdown, and overlay list. It is slightly long but every section serves a purpose—the catalog list is necessary for valid overlay selections. Front-loading the core purpose makes it easy to grasp quickly.

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?

Given the absence of an output schema, the description partially covers return behavior by noting the response is 'render-ready' and contains `series` entries. It does not detail the exact shape of each series entry, but for a charting tool with clear parameter semantics and annotations, this is adequate. The main gap is a more explicit return format, which keeps it from a 5.

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?

While schema coverage is 100%, the description significantly enriches parameter understanding: it lists allowed values for `range`, enumerates the full catalog of overlay metrics, and explains the semantic difference between `primary='price'` (candlesticks) vs a metric (line/area). Defaults are also restated and clarified. This goes well beyond the schema's basic descriptions.

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 opens with a specific verb+resource: 'Render a Santiment chart with an asset's price (OHLC) plus an optional overlay metric in a second pane.' This clearly distinguishes the tool as a chart-rendering utility compared to sibling tools like fetch_metric_data_tool, which retrieve raw data. The purpose is unambiguous and immediately front-loaded.

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 implied rather than explicitly stated. The description explains what the tool does and details parameters, but does not explicitly say when to prefer this over alternatives or provide when-not-to-use guidance. There is no direct contrast with sibling tools such as combined_trends_tool or fetch_metric_data_tool.

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