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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond that: no authentication required, unlimited free access, and return fields include value, standard error, sample size, and reporting lag. It does not mention pagination or data freshness, but the annotation coverage lowers the burden.

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?

Three sentences with no filler: purpose, sources, filtering options, return values, and auth status are all included. The most important scoping information is front-loaded, and every sentence earns its place.

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?

For a tool with 6 parameters, 4 required, and a rich schema, the description is complete enough. It covers sources, geographic levels, date range, return content, and access constraints. The output schema exists, so the return-value list is a helpful addition rather than a requirement. Minor gaps like supported time resolutions are already handled by the schema.

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 baseline is 3. The description lists source examples and return fields, but the schema already documents each parameter thoroughly. No significant additional meaning is added beyond what the input schema provides.

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 states a specific action ('Access COVID-19 epidemiological signals') tied to a concrete resource (CMU Delphi COVIDcast) and lists available data sources, filters, and return fields. This clearly distinguishes it from narrower siblings like delphi.covid.hospitalization or delphi.flu.fluview.

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 gives clear context on when to use the tool: for COVIDcast signals from multiple sources, filtered by geography and date. It does not explicitly name alternative tools or exclusion criteria, but the scope is well-enough defined that an agent can infer the intended use case.

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