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

Annotations already declare read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context: takes no board, layer coverage is per profile and not interchangeable, and get_checks reports unsupported cases rather than guessing. No contradiction with annotations.

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 description is front-loaded with the primary use case and completes with concise caveats that directly affect correct usage. Every sentence contributes either routing, scope, or a caution; there is no filler.

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?

The description fully covers what the agent needs to use the tool correctly: when to call it, what it returns conceptually, why layer coverage matters, and what not to do. The output schema handles return-structure details, so no critical behavioral information 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?

The tool has zero parameters and the schema already reflects that with 100% coverage. The description reinforces the invocation context by saying 'Takes no board,' which is useful grounding even though there are no parameters to document.

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 action ('list') on a clear resource ('fab profiles') and names the intended use with get_checks. It distinguishes itself by explaining it shows which fab houses and their limits, not just a generic list.

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?

Explicitly instructs to use before get_checks(vendor: ...) and warns not to invent a vendor id. It provides clear when-to-use context but does not explicitly describe when-not-to-use or discuss alternatives beyond the get_checks tie-in.

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