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

The annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior. The description adds useful context beyond annotations: it requires PUSHNOTIF_API_KEY, has 0 credit cost, supports zero-downtime migration export, and describes the return payload shape.

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 dense but front-loaded: purpose, usage, exclusions, requirements, and return shape all appear in a single efficient paragraph. Every sentence contributes to selection or invocation.

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?

There is no output schema, but the description compensates by naming the returned JSON fields and explaining export behavior. Given the annotations and complete parameter schema, an agent has enough information to call the tool correctly.

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%, so the baseline is 3. The description adds semantic value for export_format by explaining the full VAPID endpoint/p256dh/auth migration dump, and it clarifies app_id and tag filtering, though limit is left entirely to 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 description uses a specific verb and resource (retrieve active subscriber device records) and clearly covers the platform breakdown and export modes. It also distinguishes the tool from get_campaign_analytics and update_subscriber_tags, so an agent can select it without opening sibling schemas.

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?

It gives explicit use cases: inspect audience size, see platform distribution, export subscriber tokens, or obtain a subscriber_id before calling update_subscriber_tags. It also states when not to use it, naming both get_campaign_analytics for campaign metrics and update_subscriber_tags for modification/import.

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