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

Annotations already indicate readOnlyHint=false and destructiveHint=false, so it's a non-destructive write. The description adds meaningful context: it imports media, adds to library/uploads, returns a media_id, and does not place into a design. It also warns about URL accessibility, which is beyond the annotations. Slight gap: no mention of what happens on failure or whether it overwrites, but that's not critical.

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 four sentences, each earning its place: opening purpose, typical use cases, explicit constraints and exclusions, and return value. It is front-loaded with the core action and avoids fluff. Efficient and well-structured.

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 simple 3-parameter tool with no output schema, the description covers the essentials: what it does, when to use it, constraints, and the return value (media_id). It also clarifies what it doesn't do. No critical missing information for an agent to call it correctly, though it could optionally mention error conditions or file type limitations.

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 input schema provides 100% description coverage for all three parameters, including detailed descriptions for 'url' and 'name'. The tool description largely reiterates the URL requirement and adds the return of media_id, but doesn't add substantial new meaning beyond the schema. Baseline of 3 is appropriate given the high schema coverage.

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 and resource: 'Import media from an existing public URL into Canva.' It clearly differentiates itself from siblings by noting 'Does not place the imported media into a Canva design,' which distinguishes it from import-design-from-url. The verb 'import' and the resource 'media' are unambiguous.

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 explicit guidance: 'Use to upload a publicly hosted image...' and 'Only call with a public HTTPS URL whose content is already publicly accessible. Do not use for local, private, or agent-generated files.' It also clarifies what the tool does not do (place into design). This is direct when-to-use and when-not-to-use guidance without requiring inference.

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