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

With no annotations provided, the description carries the burden of behavioral disclosure. It reveals the important static-only constraint, but it does not disclose side effects, such as whether duplicate memberships are prevented, whether the contact must already exist, or what happens on failure. The static-audience nuance adds value, but the mutation behavior remains under-described.

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 tight sentences with no filler. The primary action is stated first, and the critical scope restriction follows immediately. Every sentence earns its place.

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 simple three-parameter endpoint with full schema coverage, the description is nearly complete: it explains the action, the target resource, and the key limitation about static audiences. Minor gaps remain around idempotency and error behavior, especially since there is no output schema to clarify expected results.

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 100 percent, so the schema already documents all three parameters as IDs. The description adds no additional meaning about how the parameters interact or what valid values look like, so the baseline of 3 is appropriate.

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 uses a specific verb and resource: 'Add a CRM contact to a static audience.' It also distinguishes this tool from sibling audience tools by explicitly scoping it to static audiences, so an agent can tell it apart from audience_create or member_remove without guessing.

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 explicitly states when to use this tool ('Only for static audiences') and when not to use it ('a saved segment's membership comes from its filter, not from this route'). This gives clear exclusion criteria and prevents misuse on segment-managed audiences.

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