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

Annotations already declare readOnly, idempotent, and closed-world, and the description adds real context: provenance (freerateupdate.com path), per-limit source attribution (FHFA vs HUD), and a last-confirmed check date. The disclaimer that results are published data, not approval or offer, further bounds interpretation.

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 sentences, front-loaded with the resource and scope, then provenance, then caveats. Slightly dense and the disclaimer sentence is long, but each part contributes orientation an agent needs.

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 takes on the return-value burden and does so reasonably: per-county limits with source and last-verified date. It stops short of naming the actual fields or handling of ZIPs with no matching county, but the essential picture is present.

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% and already documents the ZIP pattern, so the schema sets the baseline. The description still adds meaning by explaining that a ZIP can span multiple counties and that limits are returned per county, which the single 'zip' parameter alone would not convey.

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 resource (conforming and FHA loan limits), scope (counties a five-digit ZIP falls in) and vintage (2026 published schedule). The line 'a limit is not a rate' cleanly separates it from rate-focused siblings like get_mortgage_rates and get_heloc_rates.

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?

Usage is implied — the tool is for looking up published limits for a ZIP — but no explicit when-to-use/when-not or named alternative is given. The 'not advice / not a rate' caveat hints at the boundary with rate tools without routing the agent to them.

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