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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real behavioral content beyond them: the aggregation grouping (LEI), the ranking criterion and year, the derived fields returned, and a reference rendering of the same computation for output expectations. No pagination or truncation behavior is stated, which keeps it from a 5.

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?

Two compact sentences that front-load the computation and its scope before the URL reference. The final clause restates the 26-state scope already given, which is mild redundancy, though it works as deliberate routing emphasis. Little wasted text overall.

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 carry return-value expectations, and it does: ranked rows grouped by LEI, per-filer state counts, universe totals, and a concentration share. An agent knows what comes back and on what basis it is sorted. Missing only edge behavior such as empty/short-universe handling or truncation semantics.

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?

Only one parameter with 100% schema description coverage, so the schema already documents range and default. The description's 'top-25 concentration share' echoes the default limit but does not explain how limit interacts with the concentration metric or whether rows are truncated, so it adds little parameter meaning 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?

The description names the specific resource (every HMDA filer), the grouping key (LEI), the ranking metric and vintage (2025 investor-property loan count), and the computed fields (states reported in, universe totals, top-25 concentration). It also distinguishes itself from siblings by pinning scope: 'A 26-state aggregate, not a national one,' which separates it from investor_lenders_by_state and about_national_loan_provider.

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?

Scope is stated clearly enough to route an agent: 26 covered states, cross-state aggregation, not national. The closing 'not a national one' functions as an implicit exclusion against the national-scope siblings, and 'cross-state aggregate' contrasts with the by-state sibling by naming convention. It stops short of an explicit 'use X instead when you want per-state rows,' so it is context rather than full when/when-not guidance.

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