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

Adds genuinely useful behavior beyond the destructiveHint annotation: async processing, the requirement to poll printful_get_file, and idempotent de-duplication by URL. It does not contradict destructiveHint=true (a persistent file is created), but it never explains what is destructive or what permissions/lifecycle apply, so it is strong but not exhaustive.

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 short sentences, front-loaded with the action and input, then idempotency, then the async follow-up. Every sentence carries information an agent needs, with no filler.

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 create tool with no output schema, the description still covers the essentials: what is returned on duplicates and how to obtain the final result via polling. Combined with 100% schema coverage and annotations, an agent has everything needed to invoke it 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 real value by recommending PNG/JPG and clarifying that the URL is downloaded and de-duplicated server-side. This meaningfully informs the required url parameter beyond the schema's format note.

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?

States a specific verb (add), resource (a print file), and destination (the File Library) with an input constraint (from a public URL). It also references the downstream read tool (printful_get_file), which lightly differentiates it from read siblings. It stops short of explicitly contrasting with other write siblings, so a 4 rather than a 5.

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?

Gives clear context on when and how to use it: add a print file, then poll printful_get_file until status is ok. The duplicate-URL behavior (returns the existing file instead) tells the agent it is safe to re-submit. No explicit when-not or alternative-tool exclusion is stated, so 4.

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