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

Annotations already declare readOnly, idempotent and non-destructive, so safety is covered. The description goes further by disclosing the output shape (LEI grouping, loan-count ranking, per-filer state counts, universe totals, top-25 concentration) and pinning the data vintage to 2025 — context the annotations do not carry.

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 computation, then the reference URL, then the scope caveat. The URL sentence is slightly extraneous but does give a verifiable reference for the computation; overall tight.

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 must describe returns, and it does enumerate the aggregate's components (LEI groups, ranking, state counts, universe totals, top-25 share). Only the exact field naming/format is left implicit, which is a minor gap for a read-only aggregate.

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% and the single 'limit' parameter (1–50, default 25) is fully documented in the schema. The description adds nothing about the parameter, so the baseline 3 is correct.

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 operation (aggregate HMDA filers grouped by LEI, ranked by 2025 investor-property loan count) over a specific scope (15 covered states). The closing clause 'A 15-state aggregate, not a national one' lets an agent separate it from the sibling investor_lenders_by_state without opening any schema.

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?

The scope note ('15-state aggregate, not a national one') implicitly tells the agent when this tool is appropriate versus a national rollup. However, no sibling is named explicitly and there is no explicit when-not guidance, so the routing signal is only implied.

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