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

Annotations only supply destructiveHint=true, so the description carries most of the burden and does well: it discloses the membership side effect (Wild Apricot may create a membership invoice) and the flag that controls it. It does not describe the response body or error behavior for duplicate emails, though the schema notes uniqueness.

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 compact sentences, front-loaded with the core action, then the member path, then the custom-field hint and endpoint. No filler and nothing buried.

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 create tool with no output schema, the description covers the mutation's side effects and the member-vs-contact branch, which are the main agent decision points. It omits what the call returns (e.g. the new contact id), which an agent would otherwise need to chain calls.

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, but the description adds cross-parameter logic the schema cannot express: membership_enabled must be paired with membership_level_id, and the recreate_invoice interaction. That is genuine semantic value beyond field-level descriptions.

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 contact') and extends scope precisely with the member-creation path. It also names the underlying endpoint, making it trivially distinguishable from wildapricot_update_contact and wildapricot_get_contact.

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?

Gives clear conditional guidance: set membership_enabled=true plus membership_level_id to make a member, and recreate_invoice=false to suppress the invoice. It does not explicitly name alternative tools (e.g. update_contact) for the already-exists case, so it stops short of full when/when-not coverage.

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