Tag subscribers

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

Well beyond the annotations, it discloses partial-success semantics ('Emails not on your list come back in not_found and nothing else fails') and eventual consistency ('A subscriber added a minute ago may not be findable yet; try again shortly'), which is exactly the retry-relevant behavior an agent needs. It doesn't cover permissions or what removing a tag from an untagged subscriber does.

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 tight paragraphs, front-loaded with the core operation, then the batch/failure behavior, then the retry caveat. Every sentence carries distinct information with 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?

For a 3-parameter mutation with no output schema, the description covers batching limits, partial failure, and timing hazards. It stops short of describing the full return shape or any permission requirements, but nothing essential for correct invocation is missing.

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 already 100%, so the baseline is 3, but the description reinforces the two semantics that matter most: the 50-subscriber cap and the `remove` toggle direction. It adds meaning rather than duplicating the schema verbatim.

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 opening line states a specific verb and resource: 'Put a tag on subscribers by email, or take it off.' It also distinguishes itself from siblings like list_subscriber_tags, create_subscriber_tag, and tag_post by making clear this operates on subscribers (not posts) and only assigns/removes an existing tag rather than creating one.

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 gives concrete usage context: pass `remove` to take the tag off, and it points at the failure case to expect. It doesn't explicitly contrast with tag_post or add_subscriber, but the subscriber-tag scope makes the intended use unambiguous.

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