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

With no annotations, the description carries the full burden and largely meets it: it declares cost ('FREE'), a rate constraint ('Fair-use limited'), the non-obvious default behavior of slicing every candidate (quote defaults true), and real failure behavior of third-party hosts blocking server fetches. It stops short of stating side effects or auth requirements, but the disclosed behavior goes well beyond the name.

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 purpose and the key default (quote=true) are front-loaded, and the remaining sentences cover input formats, blocked hosts, and limits without filler. It is dense but mostly single-purpose; the URL-format passage is somewhat duplicated from the model_url schema description, which is the only real 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?

For a 15-parameter tool with no annotations and no output schema, the description covers purpose, defaults, and the shape of the result (reasons plus per-candidate time/filament/cost quote). The BYO pricing family is left entirely to the schema, which is acceptable at 100% coverage, but the description never signals that a pricing-override mode exists.

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 the baseline is 3. The prose restates the use_case enum and the quote default, both already in the schema, and adds a small amount of framing around model_url/model_base64. None of the seven BYO-pricing parameters are touched in the description, so it adds little beyond structured data.

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 verb and resource ('Suggest the best filament(s) for a use case') plus the distinguishing output ('a real slice/quote per candidate'), which separates it from sibling quote tools. It never names a sibling it is not, so an agent must infer the boundary against recommend_settings or get_print_quote on its own.

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?

Most guidance concerns *how* to supply input (prefer model_url, paste GitHub/Drive/Dropbox/direct file links, upload local files, blocked host pages) rather than *when* to choose this tool over siblings. There is a useful workaround loop for blocked sites and local files, but no explicit when-not-to-use or comparison against recommend_settings/compare_printers. Usage is implied by the required use_case rather than stated.

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