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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context: results are a preliminary geometric filter whose correctness depends on jurisdiction-specific setbacks and flood zone rules, which warns the agent not to treat output as authoritative. It does not describe pagination or return shape, keeping it out of the top score.

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?

Two sentences, no filler. The primary function is stated first and the caveat second, which is exactly the right front-loading for a screening tool.

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 eight parameters, no output schema and thin schema descriptions, the definition covers the core geometry well but leaves the optional filters and the shape of returned plan data unexplained. An agent can call it correctly with just required parameters, but cannot reason about what extra fields come back or how the limit interacts with results.

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 only 25%, so the description has to carry weight, and it does explain units (feet), the width/depth inputs and the role of setbacks in computing buildable area. However, several parameters — limit (capped at 25), minBedrooms and elevated — get no mention in either the description or a populated schema description, leaving those filters opaque to the agent.

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?

The description states a specific verb and resource with the mechanism: returns plans whose footprint fits the buildable area derived from lot dimensions and setbacks. That is far more precise than the name alone. It stops short of naming search_plans or explaining how it differs from that sibling, so an agent must infer the distinction.

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?

"A first screen only" gives implicit usage guidance: use this to prefilter, not to make a final determination. The follow-up instruction to confirm setbacks, flood zone and local rules with the jurisdiction and designer sets expectations about result authority. There is no explicit statement of when to prefer search_plans or get_plan instead.

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