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

Annotations already cover read-only safety, so the bar is lower, and the description clears it by disclosing a significant data-quality caveat: block dates/rates/statuses may return unknown or null due to CensoredPlanet and IODA contamination, with a review object carrying the newest evidence date. That is real behavioral context beyond annotations, though it stops short of describing output shape or limits.

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 purpose is front-loaded in the first clause, and all three sentences carry information. The middle sentence is dense but earns its length through the data-reliability caveat; minor redundancy in restating field names.

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?

With no output schema, the description does the work of outlining what comes back (dates, counts, evidence window, review object). The unknown/null semantics for block fields are covered. Missing only finer return-format detail such as date formats or multi-country response shape.

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 coverage is 100%, with both domain and country already documented and exampled in the schema, so baseline 3 applies. The description adds only the clarification that country 'focuses' one country and repeats example values, adding little beyond the schema.

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 clause names a specific verb-and-resource pair ('Measured history for one domain per country') and enumerates the returned fields (first/last measured dates, measured days, counts, evidence window). It clearly separates itself from siblings like get_most_blocked_domains or get_incident_evidence, though it never names an alternative tool explicitly.

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 shows how to invoke it ('Pass domain=twitter.com, optional country=IR to focus one country') but gives no explicit when-to-use or when-not-to-use guidance relative to siblings. The caveat about block dates being under review implies context, but the agent must infer when this timeline is the right call.

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