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 description rightly spends its words on substance the annotations cannot: dataset vintage (FY 2027, effective Oct 1, 2026), the FY 2026 carry-over flag, and the depth of historical data (back to FY 2017). It omits any note on error/not-found behavior for unresolvable counties, which is the main remaining gap.

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 with zero filler, front-loaded with the dataset and geography before the field list. It is long but each clause carries distinct information; a slight structural cost is that the returned-field list is a comma run rather than a scannable breakdown.

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, so the description correctly takes on the burden of enumerating return contents (bedroom range, FMR area, carry-over flag, 1- and 5-year change, 2BR history). Missing is any mention of behavior when the county cannot be resolved or when FMR data is unavailable for a given area.

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% — both parameters carry their own format guidance (two-letter state code; 'Travis' or 'Travis County'). The description adds no additional parameter meaning, so the baseline of 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 verb+resource: retrieve HUD FY 2027 FMRs for a single county/parish/New England town, and enumerates the exact fields returned. Geographic scope ('one county') implicitly separates it from get_fmr_by_zip and get_state_fmr_summary, but no sibling is named explicitly.

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 by the scope of the data (single county lookup). There is no statement of when to choose this over get_fmr_by_zip or compare_fmr, nor any prerequisite or exclusion such as what to do if the county name is ambiguous or unmatched.

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