Update Subscriber

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

Annotations already declare idempotentHint=true and destructiveHint=false, and the description aligns with readOnlyHint=false by stating it updates data. The description adds context that the update is limited to display name or merge fields, which is consistent with annotations and provides some additional behavioral clarity.

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 extremely concise with two sentences. The first sentence states the action, and the second provides usage guidance. No unnecessary words.

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?

Given the presence of an output schema and the moderate complexity (5 parameters, nested objects), the description adequately covers the tool's purpose and when to use alternatives. No critical gaps remain for agent selection and invocation.

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?

The description highlights the two main updatable fields (display_name and merge_fields) beyond what the schema's standard descriptions provide for audience_id and subscriber_id. While idempotency_key is not mentioned, the schema covers it. The added context helps the agent understand the primary purpose of the parameters.

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 explicitly states it updates a subscriber's display name or merge fields, using a clear verb-resource structure. It also distinguishes from sibling tools by mentioning shipmail_unsubscribe_subscriber and shipmail_resubscribe_subscriber for subscription state changes.

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 directly tells when not to use this tool by directing the user to alternate tools for subscription state changes. This provides clear usage guidance with explicit alternatives.

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