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

Adds real context beyond annotations: accepted formats, 512 KB cap, SVG rejection, the required public-https constraint, and dedup behavior ('Importing the same image again returns the same id'). The last point sits in mild tension with idempotentHint=false, but the annotation mostly concerns default engine classification, so this reads as useful disclosure rather than a 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?

Three dense sentences, front-loaded with the core action and constraints, then the return value and follow-up workflow. Every clause carries information an agent needs.

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?

Complete for a one-parameter import tool: constraints, return contract, and the exact next steps are all given, and an output schema exists so return-shape detail is not needed in the description.

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?

With a single parameter and 100% schema coverage, the baseline is 3; the description goes further by constraining the URL's scheme (public https) and the accepted image types/size, which the schema's 'Public https URL of the image.' does not fully convey.

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?

Specific verb+resource with constraints: 'Download a PNG, JPEG, or WebP image (up to 512 KB, no SVG) from a public https URL into the workspace, for a form's logo on its hosted page.' This clearly distinguishes it from generic upload/connection tools among the 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?

Explains the context (a form's logo on its hosted page) and the downstream workflow: set the returned id as theme.logo or theme.dark.logo, then persist via fillo_push_form. No explicit 'when not to use' or alternative tools are named, so it stops short of a 5.

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