List Capabilities

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

Annotations already declare readOnlyHint=true and idempotentHint=true, indicating no side effects. The description adds value by specifying the exact content of the returned metadata (generation/edit/mask/limits) and indicating it is per-model, providing useful behavioral context beyond the annotations.

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 a single, concise sentence that front-loads the key information: the action ('Return') and the target ('enabled providers and per-model capability metadata'). Every part of the sentence is informative and earns its place.

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 simplicity of the tool (one optional parameter, read-only, has output schema), the description fully explains what the tool returns. The presence of an output schema and detailed parameter documentation means the description does not need to cover return values or parameter details further.

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%, with a detailed description for the optional provider parameter listing the allowed values and their meaning. The tool description adds no additional parameter information, so 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 uses a specific verb 'Return' and clearly identifies the resource: enabled providers and per-model capability metadata including generation, edit, mask, and limits. This distinguishes it from siblings like edit_image and generate_image, which perform edits or generations rather than returning metadata.

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 implies usage for checking capabilities before calling sibling tools, but it does not explicitly state when to use this tool over alternatives. For example, it could say 'Use this to discover available providers and model capabilities before calling edit_image or generate_image.' Without such guidance, the description is adequate but not optimal.

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