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

The description adds substantial behavioral detail beyond the annotations: it discloses the required ROLA token, size limits (3.4 MB pre-encoding, 4.5 MB request), accepted formats (JPEG, PNG, GIF, WebP, AVIF), that format is detected from bytes rather than contentType or filename, and that the stored image is converted to WebP at most 1600px wide with metadata stripped. The annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=false) are consistent with a non-destructive write operation, and the description enriches this without contradiction.

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 dense but well-organized, front-loading the tool's purpose and output usage before moving to prerequisites, size limits, accepted formats, and storage behavior. Every sentence contributes essential context without redundancy.

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?

With no output schema, the description compensates by explaining what is returned ('the URL the editor stores') and how to use it. It also covers auth, size constraints, format handling, and post-upload transformation, leaving no major gap for an agent to invoke the tool correctly.

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 the baseline is 3, but the description adds critical semantics: data must be base64-encoded with a 3.4 MB pre-encoding ceiling, and the format is read from the bytes rather than from contentType or filename. This clarifies that contentType and filename do not control format detection, which is meaningful for correct invocation.

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 opens with a specific verb and resource: 'Upload an image and get back the URL the editor stores.' It distinguishes the tool by explaining how the returned URL is consumed (content block, create_page, edit_page), leaving no ambiguity about its role relative to sibling page-manipulation tools.

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?

It tells the agent exactly where to use the output—'put it in a content block as `<img src="…" alt="…">`, or pass it to create_page or edit_page as bannerImage'—which clarifies the tool's place in the workflow. It also names the required auth method ('Requires a ROLA bearer token, as create_page does'), though it stops short of stating when not to use this tool.

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