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

Annotations already declare readOnlyHint=true, and the description aligns by describing a return value. It adds behavioral context beyond annotations by specifying the index scale (0-100), data components, update frequency (annually), and the presence of decomposition, lineage, and version fields, which help the agent understand output structure without an output schema.

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 packed with information in three sentences. The first sentence is long but dense with the return value, components, and period; the 'Call when' sentence is direct and practical; the update note is concise. Minor run-on structure prevents a 5.

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?

Despite lacking an output schema, the description covers the output's key elements (index value, top_drivers, source_lineage, methodology_version) and update frequency. Combined with the schema's complete parameter documentation, it gives the agent sufficient context to select and invoke the tool correctly.

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?

The only parameter 'days' is fully documented in the schema with semantics (return daily history vs current snapshot), limits (up to 5 years), and tier requirements (Gold tier). The description itself adds no parameter information, but schema coverage is 100%, 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?

The description clearly states the tool returns a 0-100 US healthcare-access gap index and enumerates its composite components (BRFSS uninsured rates, cost-barrier-to-care, no-usual-provider rates), temporal coverage (annual since 2011), and output fields (top_drivers, source_lineage, methodology_version). This is a specific verb+resource with enough detail to differentiate it from the many sibling numeric index tools.

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 explicit call triggers covering user intents (healthcare access gaps, uninsured populations, care affordability, provider shortages, health equity) and business use cases (Medicaid network development, care-gap closure outreach, CMS network-adequacy attestations). It lacks when-not-to-use or alternative tool suggestions, so it misses the highest bar.

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