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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: the data is frozen since 2022-09-15, 'latest' means latest before the freeze, no auth required, and found=false is returned without error for missing rows. This goes beyond the annotations.

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 compact yet information-dense, with the core purpose front-loaded in the first sentence, followed by the prerequisite workflow, edge-case behavior, data source, and critical temporal caveat. Every sentence earns its place with no redundancy.

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?

The description is complete for a read-only lookup tool: it covers the prerequisite (location_search), the three dataset options, the missing-row behavior, the data source, auth requirements, and the historical freeze caveat. The output schema exists, so return values need not be described. Nothing an agent needs to call it correctly is missing.

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 the schema already documents both parameters thoroughly. The description adds the workflow hint to use location_search first, but doesn't add much beyond the schema's parameter descriptions. Baseline 3 is appropriate since the schema does the heavy lifting.

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 fetches the latest known COVID-19 statistics for one location from one of three datasets, enumerating the exact metric categories. It also distinguishes itself from the sibling location_history tool by emphasizing 'latest snapshot' semantics, and explicitly instructs to use location_search first to find a valid location_key.

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 explicitly tells the agent to use global-health-covid.location_search first to find a valid location_key, and explains the found=false behavior when no row exists. It also clarifies the data source and the historical freeze date, which prevents misuse for real-time queries.

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