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

Annotations only indicate idempotency and non-destructiveness. The description adds valuable operational details: a 1-credit cost, return of a temporary download link valid for 15 minutes, and no-browser execution. This goes beyond what annotations provide without contradicting them.

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?

Four compact sentences cover purpose, browser independence, a key series constraint, cost, and link expiry. Every sentence carries necessary information with no filler.

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 appropriately explains the return behavior (temporary link, 15-minute validity) and cost. Required parameters are fully documented in the schema. Minor edge cases like error behavior are not mentioned, but the core information an agent needs to call the tool is present.

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?

The schema describes all 7 parameters with full detail, so the baseline is 3. The description's note that pie and doughnut accept only 1 series is already present in the schema's series description, adding no additional semantic value.

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 states a specific verb ('Turns'), a resource ('labels and numeric series'), and a concrete output ('chart image'). It also explicitly lists supported chart types, making the tool's function unambiguous and easily differentiated from siblings.

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 provides clear context: chart generation from data without a browser, and the pie/doughnut one-series limitation guides correct usage. However, it does not explicitly name alternative tools or state when not to use this tool, so it stops short of full explicit routing.

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