Get subscriber growth sources

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

Annotations already carry the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds real behavior beyond them: results are ranked by source volume, scoped to a time window, and it discloses that this duplicates a get_analytics report — useful for avoiding redundant calls.

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?

Two tight sentences, front-loaded with the outcome, and the second sentence earns its place by justifying the tool's existence relative to get_analytics. No 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?

With no output schema, the description supplies the essential return shape (sources ranked by subscriber counts) and scoping. It's sufficient for a three-param read tool, though it doesn't say how many sources are returned or whether the list is truncated.

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 100% with detailed defaults and format patterns for to_date, from_date and publication, so the schema does the heavy lifting. The description only alludes to a 'window' and adds no syntax or semantics beyond that; baseline 3 applies.

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?

Specific verb+resource ('where new subscribers came from'), plus the ranking criterion and the window scope. It also explicitly distinguishes itself from get_analytics, so an agent can tell the two apart without opening either 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?

Names the alternative (get_analytics with the growth_sources report) and explains why this tool exists separately, which effectively routes the agent. It doesn't state when NOT to use it or that it is a narrower slice of the analytics tool, but the context is clear.

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