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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds that data comes from 'HUD annual FMR dataset' and is 'Free', which gives some context about data frequency and cost. However, it does not mention return format or response behavior (e.g., whether it returns a single value or a list), so it does not go beyond a minimal addition.

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?

The description is four short sentences, front-loading the core purpose and then providing context. The final 'Free.' is a minor fragment but not harmful. The structure is efficient and readable, though slightly longer than necessary.

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?

Given the tool's low complexity (2 params, no output schema), the description covers the data source, use cases, and cost, which is quite complete. It does not explain the return value format, but for a simple FMR lookup this is tolerable. The annotations cover safety, so the absence of output schema is less critical.

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?

With schema description coverage at 50%, the description does mention both parameters ('metro area and bedroom count'), partially compensating. It does not clarify that bedroom_count is optional (only metro_area is required in schema), nor does it add any syntax or format details beyond the schema's example. The description adds some meaning but not enough to fully bridge the gap.

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 clearly identifies the resource ('HUD Fair Market Rents') and its two scoping dimensions ('by metro area and bedroom count'), which is specific and distinguishes it from sibling tools like get_rental_market_benchmark. However, it lacks an explicit action verb (e.g., 'retrieves'), relying on the tool name for that, so it falls just short of a 5.

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 description provides concrete use cases ('affordable housing underwriting', 'Section 8 compliance', 'LIHTC calculations', 'housing authority budgeting'), which clearly indicate when to use this tool. It does not name alternatives or state exclusions, but the use cases alone make the intended context clear.

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