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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description does not contradict them. It adds a useful behavioral hint that this is a pre-query safety check, but it does not disclose details like how lag is measured or how missing coverage is represented.

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 a single focused sentence that front-loads the core behavior and immediately adds a practical usage tip. Every word earns its place; there is no redundancy or filler.

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?

Given the rich annotations and the presence of an output schema, the description covers the essential purpose and the key when-to-use scenario. It does not enumerate valid endpoint or zone values, but the nullable filters and sibling list tools make that a minor gap rather than a blocking one.

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 0%, so the description must compensate. The phrase '(endpoint × zone)' communicates that both parameters jointly define the scope and that they are likely optional filters, but it does not explain null/default behavior or how the parameters interact beyond the pairing.

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 opens with a specific action, 'Show ingest coverage and lag,' and clearly identifies the resource scope as '(endpoint × zone)'. This makes the tool's purpose distinct from sibling tools like get_series or list_endpoints.

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 states when to call the tool: 'call before queries if you're not sure whether the data is landed yet.' It provides clear context but does not mention when not to use it or name an alternative tool, so it stops short of full routing guidance.

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