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

Annotations declare readOnlyHint=true, so safety is covered. The description adds meaningful behavioral context beyond that: the asynchronous processing statuses (ok/waiting/failed) and the instruction to poll after adding a file, plus the preview URLs returned. It still omits auth/rate-limit/error-handling details, so not a 5.

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?

Two tight sentences plus the endpoint reference, front-loaded with what is fetched and what comes back. Every element earns its place, and the poll instruction is placed immediately after the return-value summary.

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 read-only get by ID with 100% schema parameter coverage and readOnlyHint annotations, the description supplies the missing return-value context (status fields, dimensions, DPI, preview URLs) and the key workflow trigger. No output schema exists, so this return-value summary is exactly what the agent needs.

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 description coverage is 100%, so file_id and store_id are already documented in the input schema. The description implies file_id via GET /files/{id} but adds no format, validation, or store-token semantics beyond what the schema already provides. Baseline 3 is appropriate.

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 (Fetch) and resource (one File Library entry), and enumerates the returned attributes (processing status, dimensions, DPI, preview URLs). It also names the related sibling printful_add_file, so an agent can distinguish this read-after-write tool from other 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?

Gives a clear trigger: poll this after printful_add_file, which is the primary use case. It does not state when not to use it or name alternative lookup tools, so it falls short of full when/when-not/alternatives coverage.

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