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

Beyond the readOnlyHint and idempotentHint annotations, the description adds valuable behavioral context: the data reflects live, changing coverage ('RIGHT NOW', 'coverage deepens daily toward the backfill horizon') and includes access-tier information. This helps the agent understand the dynamic nature of the response.

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 two sentences with no filler. The first sentence front-loads the tool's purpose and what it returns; the second gives direct invocation guidance. Every clause 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 zero-parameter orientation tool with no output schema, the description sufficiently covers what the agent will receive: per-feed live date ranges, access tier, and example questions per tool. It also tells the agent when to call it, making the description complete for correct invocation.

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 tool has zero parameters and the schema already describes an empty object. No parameter-level documentation is needed, so the description correctly focuses on output content and usage context rather than input semantics.

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 clear verb-resource pair: 'describe coverage' of the server's per-feed date ranges, access tier, and example questions per tool. It also positions itself as an orientation tool distinct from the domain-specific sibling tools, so an agent can easily tell them apart.

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?

It gives explicit guidance: 'Call this first when unsure what to ask or whether a date range is covered.' This establishes clear usage context, though it does not enumerate when-not-to-use alternatives.

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