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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and openWorld, so the safety profile is covered. The description adds that the data comes from a 'self-hosted official snapshot' and mentions a snapshot hash and required attribution, which is useful provenance context. It does not add further behavioral detail such as rate limits or exact pagination semantics, so a 3 is appropriate.

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?

Four sentences, front-loaded with the core purpose, followed by returned fields, usage examples, and a scope clarification. No wasted filler. The final sentence earns its place by preventing misuse as a valuation tool.

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 annotations covering safety and a fully-described 10-parameter schema, the description covers purpose, return fields, provenance, and a key scope limit. It could be stronger by explicitly routing users to fhfa_hpi_trend and fhfa_hpi_compare, but it is otherwise complete for a read-only index query.

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%, so every parameter is already documented in the schema, establishing the baseline of 3. The description adds no syntax or format detail beyond the schema (e.g., no guidance on how place names are matched), so it does not exceed baseline.

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 and resource ('Return a bounded FHFA House Price Index history for one US geography') and enumerates the returned fields including stable place_id, geography level, year/period, and both index flavors. It does not explicitly contrast itself with the sibling tools fhfa_hpi_trend and fhfa_hpi_compare, so it falls short of full sibling differentiation.

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 concrete example queries ('show California house-price history', 'chart the Austin metro HPI') and names a use context ('as a federal price-index leg alongside realestate_trend'). However, it never states when NOT to use it versus the closer siblings fhfa_hpi_trend and fhfa_hpi_compare, leaving the boundary ambiguous.

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