find_by_vision

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

Annotations already declare readOnlyHint=true, lowering the bar. The description adds valuable behavioral context: it takes a screenshot, delegates to an external model, and requires specific API keys. It discloses the external dependency and authentication needs 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?

Three sentences, each purposeful: first states the action, second gives usage guidance, third lists prerequisites. No fluff or redundancy. Information is front-loaded with the tool's purpose.

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?

The description covers purpose, usage context, and prerequisites. Since there is no output schema, the return behavior is partially covered by the responseFormat parameter's schema description, so the tool description need not repeat it. Minor gaps like potential errors or rate limits exist, but given the rich schema, the description is sufficiently complete.

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 the schema already explains each parameter's meaning, including the API key mapping for 'model'. The description adds no new parameter semantics; it just repeats the API key information already present. Thus the baseline score of 3 is appropriate.

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 the tool's function: 'Take a screenshot and delegate visual analysis to an external vision model, returning the result.' It uses a specific verb and resource, and explicitly distinguishes itself from alternatives with 'Use when visual analysis should be performed by a separate model rather than by the calling agent.' This differentiates it from sibling tools like find_element or analyze_screen.

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?

Provides clear contextual guidance by specifying when to use: 'Use when visual analysis should be performed by a separate model rather than by the calling agent.' It also lists required API key prerequisites. However, it does not explicitly name alternative tools or state when not to use it, so it misses the top score.

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