Add subscriber to sequence by email address

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

Annotations already declare destructiveHint=true, readOnlyHint=false and idempotentHint=false, so the safety profile is covered. The description nevertheless adds value by naming the blast radius (delivery, audience membership, published data, irreversible state) and the confirm=true precondition, going beyond what the structured fields state.

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 short sentences, action and identifier front-loaded, consequence and precondition packed into the second. No filler or restated boilerplate.

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?

For a destructive, non-idempotent mutation with a nested payload and no output schema, the description covers purpose, risk scope and the confirm gate adequately. Minor omissions: it doesn't flag that payload and payload_file are mutually exclusive nor that this is the email-keyed alternative to the by_id tool, but the schema handles the former.

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 83%, so the schema carries most parameter meaning (account, payload/payload_file mutual exclusivity, email_address, sequence_id format). The description only echoes the confirm requirement already documented in the schema, adding little beyond the structured fields – the baseline 3 for high coverage is appropriate.

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 (Add), resource (subscriber), container (sequence) and the identifier method (by email address). The 'by email address' phrasing cleanly distinguishes it from the sibling add_subscriber_to_sequence_by_id without needing to open 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?

The description gates the call with 'Requires confirm=true' and warns of consequences, which is real usage guidance. However, it never says when to prefer this email-based variant over add_subscriber_to_sequence_by_id, or that self-service use is inappropriate (that constraint lives only in the schema for 'confirm').

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