upsert_member

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

Annotations already declare idempotentHint=true; description adds 'idempotent upsert', authentication method, max 10 concurrent requests, and respects read-only/dry-run modes. No contradiction.

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?

Well-structured: purpose, usage guidance, constraints, parameter list with details, return value. No unnecessary sentences. Efficiently uses space.

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?

Output schema exists (though not shown) and description enumerates return fields: id, email_address, status, merge_fields, tags, list_id, timestamps. Also mentions error object. Covers all necessary context for an upsert operation.

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 has 0% description coverage, but the description fully explains each parameter: list_id format and source, email_address (subscriber hash derived), status_if_new valid values, merge_fields example, tags as list, account naming convention. Compensates completely.

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 clearly states it adds or updates a member (idempotent upsert). It distinguishes from siblings add_member (strict create) and update_member (modify only).

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?

Explicitly says when to use (reliable add-or-update without existence check) and when to use alternatives (add_member for create, update_member for update). Also mentions authentication and concurrency limits.

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