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

Annotations already flag destructive and idempotent; the description adds real context on top: only passed fields change (partial-update semantics) and the concrete effect of disabling (member can no longer participate in programs). It does not describe the failure mode when the member is not uniquely identified, nor what the response contains.

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 sentences, front-loaded with the WRITE marker and the capability, then update semantics, then identification rules. No filler.

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 12-parameter mutation tool with no required params and no output schema, the description covers mutation semantics and lookup requirements well. Gaps remain around ambiguous-match behavior and confirmation of what is returned.

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 coverage is 100%, so the baseline is 3; the description nevertheless synthesizes the identifier combinations into one rule (id, referral code, or email/external_id + program), which is more than restating individual field docs. It still leaves the current-vs-new field pairing (e.g., email vs new_email) to the schema.

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?

Opens with a specific verb class ("WRITE") plus the resource and scope: changing contact details, or disabling/re-enabling a member. It is clearly separable from sibling create_member (creation) and update_referral (different resource).

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?

States the identifying conditions (id, referral code, or email/external id plus program_id/program_name) and that the member must be uniquely identified. It does not explicitly name create_member or list_members as alternatives for when the member does not yet exist or must be found first.

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