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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: the data provenance (CFPB HMDA 2025 record), the exact filter methodology (actions 1,2,3; loan_type 2), the applicant-mix caveat that any comparison must carry, and an explicit 'not a prediction' disclaimer.

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 answerable questions and then labels each block (PARAM, COVERS ONLY, NOT FOR), which is easy to scan. It is dense and somewhat verbose with repeated question variants, but each section carries routing or scope value.

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 compensates by enumerating what is returned (volume, denial rate, rank, caveat) and by bounding the population covered. An agent has everything needed to call it and interpret the result correctly.

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 description coverage is 100% for the single 'lender' parameter, so the schema already documents accepted formats. The description's 'PARAM: lender name, slug or LEI' restates rather than extends that, so the 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 resource (a lender's FHA denial rate) with concrete example questions and a clear scope (2025 decisioned volume, denial rate, rank). It is readily distinguishable from siblings like get_state_denial_stats and get_national_fha_stats by naming the lender-level unit of analysis.

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?

Provides explicit when-to-use triggers (the quoted user questions) and explicit exclusions under 'NOT FOR: whether a person will be approved, or lenders outside that set', plus a stated coverage limit of the 100 largest FHA lenders. Nothing about routing 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.