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

Annotations already cover the safety profile (readOnly, idempotent, not destructive, closed-world), so the bar is lower; the description still adds useful context — only licensed states answer, results include as-of time and source page, and legal disclosures travel with the data. It doesn't say what happens on an unlicensed state or a missing county, 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?

Front-loaded with the core purpose and packed efficiently into one long sentence with a parenthetical clarifier. Slightly dense — the trailing Spanish aside could be trimmed — but no sentence is wasted.

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 compensates by enumerating the returned fields (rate, APR, points, closing costs, pricing scenario, as-of time, source page, disclosures), and annotations cover the safety semantics. An agent has everything needed to call it and interpret the result.

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, including enums and the Spanish/language behavior. The description restates the program lineup and the language=es flag but adds no syntax or edge-case detail beyond the schema, so 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?

States a specific verb and resource ('Today's published CapCenter mortgage rate tables for a county') and enumerates exactly what each row contains (rate, APR, points, zero closing costs) plus the programs covered. That level of specificity clearly separates it from siblings like get_mortgage_quote (personalized quote) or compare_refinance_options.

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 implies usage (look up published rate tables for a county, with program/purpose views) but never states when to choose this over get_mortgage_quote, compare_refinance_options, or explain_loan_options. The `purpose` purchase/refinance view is mentioned only indirectly via the schema, not as guidance.

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