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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is field-level caveats — and it delivers two: lag_hours measures time since success rather than upstream backlog, and source_latest_known is not yet reported and remains null. That prevents a common misreading of a null value. It stops short of anything about refresh cadence, caching, or how stale the stored results themselves may be.

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?

Four short sentences, zero filler, front-loaded with what is returned before the alternative-tool routing and the field caveats. Each sentence carries distinct information an agent would otherwise have to guess at.

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?

A zero-parameter read tool with an output schema and full annotation coverage needs little more than this: what it returns, when to pick it over siblings, and the two gotchas in the payload. Nothing required for a correct invocation 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?

The tool takes no parameters, so there is nothing for the input schema to document and the baseline is 4. The description instead spends its words on output-field semantics (lag_hours, source_latest_known), which is a sensible use of the space.

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 opening sentence states a specific verb and resource ('Return source import and extraction times from stored study results'), then names the sibling tool covering nearby territory (get_changes for record events, get_my_usage for quotas). An agent can distinguish this from all fourteen siblings without opening a schema.

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?

Explicit when-to-use ('inspect data freshness') paired with two named alternatives and the condition that selects each ('record events', 'caller quotas'). This is exactly the routing information an agent needs given the crowded sibling set.

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