marks

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

No annotations are provided, so the description carries full burden. It discloses the capture behavior, reliance on accessibility tree, fallback to plain legend when ImageMagick is absent, and a note when no tree exists. It does not mention destructive actions, rate limits, or authentication, but these are not critical for a read-like capture tool.

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 moderately long but all sentences serve a purpose: core functionality, usage advice, fallback conditions. It is front-loaded with the primary action. Minor redundancy (e.g., 'Falls back...') could be more concise, but overall well-structured.

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 complexity of fallbacks (ImageMagick, no tree) and the presence of an output schema (return values not needing further explanation), the description covers all necessary context: parameters, output (JSON legend), and use case. It references sibling tools appropriately.

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?

With 0% schema description coverage, the description adds meaning: `window` is 'an address from desktop (default: focused)' and `name` 'filters the marked controls'. It does not specify the exact format of the window address, but provides enough context for the agent to use parameters correctly.

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 clearly states that the tool captures a screenshot with numbered red marks and a JSON legend mapping each mark to control details. It uses the specific verb 'capture' and resource 'Set-of-Marks', and distinguishes from siblings like 'screenshot' and 'ui' by highlighting marks and legend.

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 explicitly advises when to use the tool: to replace the 'estimate-zoom-estimate loop' for controls in the accessibility tree. It provides follow-up actions (using `click_ui(mark=N)` or `pointer`), and specifies fallbacks for missing ImageMagick or no accessibility tree, with an alternative (screenshot + zoom).

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