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

The description discloses key behavioral details beyond annotations: it performs outpainting, has three speed tiers with specific credit costs, and returns a new image URL. It does not contradict annotations (readOnlyHint=false, etc.) and adds useful cost/performance trade-off information. Minor gaps remain about side effects or rate limits, but for a creative tool this is solid.

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 two concise sentences, front-loaded with the core purpose and then providing the essential parameter and return information. Every sentence earns its place with no fluff or repetition.

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 tool with only 3 parameters and no output schema, the description covers the main functionality, inputs, speed/cost options, and return value. It does not mention limitations like max file size or file format restrictions, but given the openWorldHint and simple nature, the description is nearly 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?

The schema already covers all three parameters with 100% description coverage, including the enum values and credit costs. The description reinforces the aspect ratio examples and speed tiers but adds no new parameter-specific meaning beyond what the schema provides, so the baseline of 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?

The description clearly states a specific verb ('Reframes') and a specific resource ('image') with a clear goal ('to a new aspect ratio'). It distinguishes itself from siblings like reframe_video and edit_image by focusing on image reframing via outpainting.

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 gives clear context for when to use the tool (when needing to reframe an image to a new aspect ratio) and explicitly lists the required inputs and speed options. It does not explicitly name alternatives or state when not to use it, but the sibling list and specific language make the usage context obvious.

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