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

Annotations already cover safety (readOnly, idempotent, closed-world), so the bar is lower; the description adds real semantic guarantees about aggregation ('never sums repeated snapshots', 'never treats missing metrics as zero') that an agent cannot get from the schema or annotations.

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 tight sentences, front-loaded with what it returns and immediately followed by the disambiguation. The phrasing is dense but every clause carries routing or semantic information.

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?

An output schema exists, so return values need not be described, and the selection guidance is complete. The only gap is the undocumented brandId parameter and no hint about period semantics, e.g. how since/until interact with 'lifetime' metrics.

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% across three required params, so the description must compensate. It conveys that since/until define the reporting period, but says nothing about brandId, leaving a required identifier undocumented anywhere.

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?

States a specific verb (summarize) and resource (latest saved lifetime metrics for posts in the selected period), and explicitly contrasts with 'Not daily account activity', separating it from get_analytics.

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?

Gives explicit routing: saved X and channel reports go to get_report_capabilities and get_channel_report, fresh reports go to request_channel_report, with a stated exclusion for daily account activity. No inference required.

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