Create a subscriber

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

Annotations already declare destructiveHint=true, readOnlyHint=false and openWorldHint=true, so the mutation profile is covered. The description adds the confirm=true requirement and a vague impact warning ('delivery, audience membership, published data or irreversible state'), but does not say what specifically is destroyed or whether a re-created subscriber restores prior 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?

Three short sentences with the action front-loaded and no filler. The impact sentence is a slightly generic laundry list that could be tightened, but nothing is wasted.

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 an 8-parameter creation tool with nested objects, no output schema, and three competing body-supply mechanisms, the description should clarify which input style to use and what a successful create returns. It covers the confirm gate but leaves the biggest agent decision (payload vs. payload_file vs. flags) entirely to the schema.

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 75%, so most parameters (state enum, fields, account, payload, payload_file) are already documented in the schema. The description adds only the confirm prerequisite, and notably omits how the mutually exclusive payload/payload_file/individual-flag styles should be chosen, which is the highest-value missing guidance.

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 and resource ('Create a subscriber'), which is clear on its own and separable from siblings like update_subscriber and delete_subscriber. It does not, however, distinguish itself from bulk_create_subscribers or explain why one would pick this over the bulk variant.

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 only usage guidance is the 'Requires confirm=true' prerequisite, restated from the schema. There is no indication of when to use this single-create tool versus bulk_create_subscribers, nor any prerequisites such as existing account/audience setup, though the sibling-heavy context makes that routing decision non-trivial.

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