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

Annotations only say it is a non-destructive, non-idempotent mutation. The description adds real behavioral context beyond that: the drawing persists on the chart and appears in films of that window, points must be in the past, lime ink is refused, and path points must move forward in time. It does not explain confirmation or reversal behavior.

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?

Front-loads the action and the supported shapes, then layers constraints and side effects. Dense but every clause carries information; the only expendable flourish is the parenthetical about lime and the fire.

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?

For a 5-parameter mutation with no output schema, the description covers the operation, per-kind anchor rules, price/time sourcing, ink restrictions, and the visibility side effect. It leaves only minor gaps around confirmation and how redrawing of the same anchor is handled.

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 baseline is 3, but the description materially enriches it by mapping each kind to its point requirements (line=two points, box=two corners, path=2-24 forward-moving points, note=one point plus a short word) and explaining why the lime enum value is unavailable. That goes beyond the enum lists and terse schema 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?

Opens with a specific verb and target ("Draw on the trader's chart") and enumerates the exact artifact types it produces (line, box, path, note), each with its anchor count. An agent can distinguish this from siblings like erase and drawings purely from the text.

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?

"as they ask" and "a price the trader gave or the tape tool returned; never invent a level" imply this is user-initiated and constrain the price source, which is useful. However, there is no explicit statement of when to use this versus erase/drawings, nor prerequisites such as needing an open chart window.

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