chart_extract

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

No annotations are provided, so the description carries the full burden, and it partially discharges it by disclosing the return structure ({series:{name:{points,min,max,zero_crossings,coverage}}}) which is not in any output schema. However, it says nothing about failure modes (e.g. too few ticks, unmatched colour), what 'coverage' or 'tol' mean operationally, or any resource/permission constraints.

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?

A single compact sentence that front-loads the action and the output shape. The arrow-and-brace notation is dense but information-bearing; nothing is wasted.

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 doing pixel-to-axis calibration, the description is thin: it covers the return shape but not the coordinate/calibration model or the colour-matching semantics. It is minimally adequate given the 86% schema coverage, but an agent would likely need trial and error.

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 86%, so the schema already documents most parameters including the terse [px,value] tick format. The description adds nothing about the tricky parameters (plot_region, series rgb/tol, samples default) beyond implying series names surface in the output, so the baseline 3 applies.

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 ('Read coloured curves in axis units') and even sketches the return shape. An agent can tell it apart from siblings like ocr_region or track_text, though it does not explicitly name a sibling or state the conversion pipeline.

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?

There is no when-to-use guidance, no prerequisites (e.g. video must already be loaded/known path), and no mention of alternatives among the sibling tools. The agent must infer applicability purely from the name and description.

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