Update a subscriber

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

Annotations declare destructiveHint=true and idempotentHint=false, and the description adds value beyond that: it warns that delivery, audience membership, published data, and irreversible state may be affected. That's a meaningful behavioral disclosure. It stops short of naming what exactly is irreversible or how failures are handled.

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 sentences, front-loaded with purpose, followed immediately by impact and requirement. No waste, very high signal density.

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 complex mutation tool with nested objects and no output schema, it gives the essential impact and confirmation requirements. It omits the mutually exclusive relationship between payload and body flags, and doesn't reference warnings handling, but is otherwise sufficient.

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 75%, so the schema already carries most parameter meaning. The description adds the crucial semantics that confirm=true is required and must be user-requested, which the schema also states but the description reinforces. It doesn't explain the interaction between payload, payload_file, and body flags, which is a notable gap for 8 params.

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 clear verb+resource ('Update a subscriber'), enough to distinguish from get_subscriber, create_subscriber, delete_broadcast, etc. But it doesn't distinguish from sibling update tools like bulk_update_subscriber_custom_field_values or update_subscriber_location, which is a real ambiguity given many subscriber-related updaters exist.

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?

Clearly states that confirm=true is required, which is when-to-use guidance. It implies this is a mutating tool. But it doesn't say when to prefer bulk_update_subscriber_custom_field_values or other subscriber-update siblings, so context is clear but alternatives aren't named.

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