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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is largely covered; the description's 'Read-only, no side effects' is partly redundant. It does add non-annotation context — 'no authentication' and 'returns public metadata' — which meaningfully informs invocation. Minor overlap 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 purpose, then the when-to-use routing, then the behavioral traits — a sensible order. The single dense sentence with em-dashes is a bit long, but every clause (plan contents, alternatives, auth/side-effect status) contributes.

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?

Output schema exists, so return values need not be explained, and the description still summarizes what the plan delivers. With annotations covering safety, 100% schema coverage, and clear sibling routing, nothing an agent needs to invoke this correctly is missing.

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% with per-parameter descriptions and an enum for framework, so the schema already carries the semantics. The description adds only indirect framing ('a described project') and does not clarify the optional industry/framework parameters beyond what the schema states. 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 and deliverable ('return an OPINIONATED BUILD PLAN') and spells out the plan's contents (catalog assets, Three.js/WebGL architecture, framework choice, performance guidance). It explicitly distinguishes itself from search_3d_web_assets and list_3d_web_categories, so an agent can route correctly without opening the 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?

Gives an explicit trigger ('when the user describes something to BUILD rather than an item to look up') and names two alternatives with the conditions that select them: search_3d_web_assets for a plain ranked list, list_3d_web_categories for the taxonomy alone. Nothing is left to inference.

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