send_image_as_user

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

With no annotations, the description carries full disclosure burden. It reveals important behaviors: sends as logged-in user, needs image_key from upload, requires thumbnailKey in wire format (defaults to imageKey), and that metadata is optional. It does not mention return values or error cases, but covers the critical nuances.

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 front-loaded with purpose and includes essential technical detail. It is slightly verbose with version and wire-format specifics, but each sentence contributes value, making it appropriately sized for the tool's complexity.

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 8 parameters and no output schema or annotations, the description covers purpose, prerequisites, and key behavioral details. It lacks explicit discussion of return values or when to use alternatives, but the overall context is sufficient for an image-sending tool.

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%, so baseline is 3. The description adds meaningful context beyond schema: it clarifies the image_key source, explains the thumbnail_key fallback behavior, and notes that width/height/mime/size are optional and auto-derived. This enriches parameter understanding without duplicating schema text.

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 states a specific action ('Send an image as the logged-in user') and clearly distinguishes itself from bot messaging with 'NOT bot'. It also specifies the prerequisite (requires image_key from upload_image), making the tool's purpose unmistakable.

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 conveys clear usage context: use this tool to send images as the user, requires a prior upload_image call. It also explicitly contrasts with bot sending, but does not name alternative sibling tools beyond that implicit distinction.

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