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

With no annotations, the description carries the burden and does disclose meaningful behavior: the pipeline of operations performed (dedup, instance, join, weld, simplify, resize/re-encode textures, meshopt/draco) and the cost model ($0.20 USDC via x402, charged only on success). It omits return/output behavior and any timeout or size-failure handling, but the billing and transformation disclosure is substantial.

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 purpose and cost, then summarizes the toolkit. The trailing 'Part of GLB optimizer:' colon-list is somewhat run-on and partially redundant with the opening sentence, but overall the text is dense and earns its space.

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 7-parameter tool with no annotations and no output schema, the description covers purpose, cost, and the size boundary but leaves key gaps: which input (glb base64 vs glbUrl) to supply, and how the optimized artifact is returned given no output schema. Adequate but incomplete.

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 only 29%, so the description must compensate, and it largely does not: it restates enum values already present (web/mobile/preview, meshopt/draco) while leaving glb vs glbUrl selection, simplifyRatio, maxTextureSize, and textureFormat behavior unexplained and the mutual exclusivity of the two input sources undefined.

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 and resource ('Optimize a GLB') plus an explicit scope bound ('up to 10 MB') and the preset modes, which lets an agent distinguish it from the sibling glb_optimizer_optimize_large without opening either schema.

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?

The 'up to 10 MB' bound and the preset list give clear context for when this tool applies, and the pricing note frames the cost decision. However, it never names glb_optimizer_optimize_large as the alternative for larger files, leaving the routing to inference.

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