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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered. The description adds one useful piece of context the annotations lack: the matplotlib runtime dependency. It says nothing about output (image object, base64, or file path) or limits on data size, though the 10,000-item caps are visible in the schema.

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?

One sentence, zero filler, and the essential dependency note is included. Nothing could be removed without losing information, and nothing important is buried.

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 7-parameter tool with full schema coverage and safety annotations, the definition is minimally adequate. The notable hole is the return contract: with no output schema, the agent cannot tell whether this returns an image, a file path, or nothing, which matters for a chart-rendering 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 carries an example and default, so the schema does the heavy lifting. The description adds no parameter meaning beyond 'data points', which is the baseline 3 case when the schema is self-sufficient.

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 ('Create a scatter plot from data points'), which is unambiguous on its own. However, it does nothing to distinguish it from the five sibling plot_* tools (plot_line_chart, plot_histogram, plot_box_plot), so an agent choosing between chart types gets no routing help.

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 gives no when-to-use guidance, no conditions, and no alternatives. With five sibling plotting tools available, the absence of any routing signal (e.g., scatter for correlation between two variables vs line for trends) is a real gap.

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