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

Annotations already cover read-only, idempotent, non-destructive and closed-world, so the bar is lower, yet the description still adds material context: the 100-decisioned-application inclusion threshold, the underlying source slice (CFPB HMDA 2025, actions 1,2,3, loan_type 2), the fact it is a historical observation and not a prediction, and the CC BY 4.0 attribution requirement.

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 ANSWER queries, then PARAM, then Returns, then NOT FOR, then caveats and attribution — a clean priority order. The trailing licensing sentence is necessary for compliance but is the one part that does not help invocation.

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 carries the full burden of describing the return value and does so: a claim passport containing lowest/highest lender denial rates, the gap in points, counts and a source reference. Combined with the inclusion threshold and provenance notes, an agent has everything needed to call and interpret it.

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 the single 'metro' parameter is already documented with the same name-or-slug example, so the description's 'PARAM: metro name or slug' adds nothing beyond the schema. Baseline 3 applies.

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+resource (returns the lender denial-rate spread within a single metro) and pins it with a concrete example (Cleveland, 73.7 points, 6.4 vs 80.1). It is clearly distinguishable from siblings like get_lender_denial_stats, get_state_denial_stats and get_national_fha_stats because the scoping unit — one metro — is stated up front.

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 when-to-use as four literal user questions, plus explicit exclusions: not ZIP/neighbourhood questions, and never as evidence a lender acted improperly. It does not name the sibling an agent should use instead for those excluded cases, which is the only gap.

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