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

Annotations already declare it is non-read-only, idempotent, non-destructive, and closed-world, so the bar is lower. The description nevertheless adds real value: the download link expires in 30 minutes and the fidelity of STEP output depends on whether the source was read exactly, which is the key caveat an agent needs. It does not mention the async/running status behavior, but the schema's wait_seconds covers that.

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 tight sentences: purpose and return value first, then the fidelity caveat, then the mesh-format rule. Every sentence carries distinct information and nothing is redundant.

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?

With no output schema, the description properly discloses the return value (download link, 30-minute expiry) and format trade-offs. The only gap is not describing the status=running polling outcome, which the schema only hints at via wait_seconds.

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 baseline is 3, but the description adds meaning beyond the schema by explaining what the solid-vs-triangulated STEP distinction actually implies for downstream editability in CAD software. That interpretive context is not in the enum description.

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 (convert), the resource (a file opened with inspect_cad), the three supported targets, and the return value (download link). It also implicitly distinguishes itself from inspect_cad by naming it as the prerequisite step.

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?

"Convert a file opened with inspect_cad" gives a clear prerequisite that selects this tool over its sibling. It does not state when not to use it or what to do with an upload_ticket flow (the schema covers the latter), so it stops short of full routing guidance.

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