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

Annotations already carry readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely new context beyond those flags: the data vintage (2025 HMDA loan-level), the retrieval date in the payload, and the caveat that figures are the filing record rather than a recommendation. What it does not disclose is pagination or truncation behavior relative to the limit.

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?

A single dense sentence that front-loads the scope (top investment-property lenders, one state) before the data source and returned fields. Nothing is padded, though cramming the field list and the disclaimer into one sentence makes it slightly harder to scan than a short two-line split would.

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?

There is no output schema, and the description compensates by enumerating the returned fields (lender name, LEI, loan count, volume, average loan, purchase share, plus state totals and retrieval date). That is close to complete for a two-parameter read tool; only ranking basis and limit/truncation behavior are unspecified.

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%: 'state' enumerates the 26 valid codes and 'limit' documents its 1–50 range and default. The description adds no syntax or format detail beyond that, so the baseline 3 is correct when the schema does all the parameter work.

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: it returns top investment-property lenders for a single state, sourced from 2025 HMDA loan-level data. That is enough to separate it in spirit from investor_lenders_aggregate, but the description never names or contrasts the sibling, so the differentiation is left to inference.

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 only implied: 'in one of the 26 covered states' signals that this is the per-state slice, which hints at when to pick it over the aggregate sibling. There is no explicit when-to-use, when-not-to-use, or named alternative, so it stays at minimum-viable guidance.

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