Tag a subscriber by email address

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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds concrete consequences (delivery, audience membership, published data, irreversible state) that go beyond the boolean hints, plus the confirm gate. It stops short of noting that repeat calls are not idempotent, which the annotations only hint at.

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 short sentences with the purpose front-loaded and the confirm requirement last. No filler, though the risk list is somewhat boilerplate and could be tightened.

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?

Covers the mutating nature and the confirm gate for a 6-parameter tool with no output schema. The identifier and body-input alternatives (payload vs payload_file vs body flags) are left entirely to the schema, so an agent gets only a partial picture of how to invoke it.

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 83%, so the schema carries most parameter meaning; the baseline applies. The description only reinforces the email-address selector and the confirm requirement, adding little about payload, payload_file, or account over what the schema already documents.

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?

Names a specific verb (tag) and resource (subscriber) with the identifying key (email address), which implicitly separates it from the sibling tag_subscriber_by_id. It does not explicitly name that sibling, so it stops short of a 5.

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?

States the prerequisite that confirm=true is required, which is actionable. However, it gives no guidance on when to prefer this over tag_subscriber_by_id, bulk_tag_subscribers, or untag_subscriber, so usage selection is implied rather than directed.

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