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

With no annotations, the description carries the full burden and does well: it discloses that the operation is non-mutating, lists the return shape (part_price / total / order_url), and warns the output is desensitized (no unit prices) — a non-obvious behavioral trait. It omits auth/permission requirements, which keeps it from 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?

Front-loads the core action before enumerating inputs, and each clause adds information (inputs, precedence, exclusion, return shape). Dense but largely waste-free; the uppercase emphasis and dashes make it slightly busy.

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?

No output schema exists, but the description compensates by naming the returned fields and the desensitized nature of the response, plus the required inputs. An agent has enough to call it correctly; only auth/error behavior is unaddressed.

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 3 is the baseline, but the description adds the weight_g/volume_cm3/file_key precedence and the provenance of file_key (uploaded via /v1/uploads/presign + /v1/uploads/complete, parsed for volume) — workflow detail not present in the schema.

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 (CALCULATE) and resource (3D printing price), and immediately rules out the adjacent action with 'This tool does NOT create an order.' The pricing focus clearly separates it from the material/equipment/process comparison 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 clear context for invocation (the required part fields and the weight_g vs volume_cm3 vs file_key choice) and an explicit exclusion ('does NOT create an order'). It never names an alternative sibling or states when a different tool is preferable, 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.