add_circle

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

No annotations are provided, so the description bears the full burden of behavioral disclosure. It only says 'draw a circle on the image,' which implies a mutation (changing the image) but does not disclose whether the operation is reversible, whether it overwrites existing annotations, what state changes occur, or any side effects. There is no mention of permissions, limits, or error behaviors. This is minimal disclosure that leaves the agent guessing about consequences.

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 consists of a single, clear sentence with no redundant words. It is front-loaded with the action and resource. However, it is so sparse that it borders on under-specification rather than effective conciseness. It earns its place by stating the purpose, but it omits any context that would make it more useful. The structure is efficient, but the brevity limits its value.

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 tool has 7 parameters and an output schema, the description should at least mention when to use it, prerequisites, and what happens, but it only states the basic action. It does not explain return values (though output schema exists, it may cover that), nor does it provide usage context or side effects. For a drawing tool, an agent needs to know if it mutates the image, if it is reversible, and what coordinate system is used—none of which are disclosed. The description is inadequate for safe and correct invocation without external knowledge.

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%, meaning all 7 parameters (image_id, x, y, radius, fill, color, line_width) are fully described in the input schema with titles and descriptions. The tool description adds no additional semantic clarity beyond what the schema already provides. Since the schema handles parameter meaning comprehensively, a baseline score of 3 is appropriate, as the description does not compensate for any gaps but also does not need to.

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 'Draw a circle on the image' states a specific verb and resource (draw on image), and clearly differentiates from sibling tools like add_box, add_line, etc. by naming the shape. However, it lacks any additional specificity (e.g., coordinates, styling) that the schema provides, and it does not mention why an agent should choose this over other annotation tools. Still, the core purpose is unambiguous and distinct from its siblings.

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 provides zero guidance on when to use this tool versus alternatives. It does not state any prerequisites (e.g., image must exist), exclusions (e.g., not for other shapes), or contexts where this tool is preferred. An agent is left to infer usage from the name alone, which is insufficient for a tool with many sibling annotation tools.

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