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

With no annotations provided, the description fully carries the behavioral burden. It discloses idempotency, defines the no-op success case, and details exactly what effects are revoked: removal from `list_subscribers` results and loss of the subscriber's ability to call `list_subscribers` for that tag. This is rich, precise behavioral transparency.

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 two sentences with no filler. The primary purpose is front-loaded immediately, followed by the idempotent behavior rule, and then the precise consequences. Every sentence contributes substantive information.

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 two-parameter tool with no output schema and no annotations, the description completely covers the essential context: what happens, what is unaffected (no-op for non-subscribers), and what observable effects occur. An agent has enough information to call and interpret 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 description coverage is only 50%, with the required `tag` parameter left completely undescribed. The description does not add meaning to `tag` beyond naming it as the subscription target, and it does not compensate for the missing schema documentation of that parameter. `owner_key` is well explained in the schema, but the description adds no parameter-level value.

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 opens with a specific verb and resource: 'Unsubscribe the caller's account from a tag.' It clearly distinguishes itself from `subscribe_tag` by explaining what the operation reverses, and from `list_subscribers` by describing downstream effects. The phrase 'Immediately revokes the two things `subscribe_tag` granted' makes the tool's role unambiguous.

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 implies the tool is used to undo a subscription created by `subscribe_tag`, and explains the consequences. However, it does not explicitly state when to choose this over alternatives or note any exclusions, such as when the caller is not subscribed. Usage guidance is present but mostly inferred from context.

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