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

Without annotations, the description must carry the full burden. It discloses the upsert behavior and case-insensitive matching on name, which is genuinely useful. However, it does not state what happens when only name is provided (e.g., whether existing phone/email are cleared) or what response/error behavior to expect.

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?

Two short sentences with no filler; the key information is front-loaded. Perfectly sized for the simplicity of the tool.

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 three-field upsert with a single required parameter, the description gives the agent the essential semantics: create-or-update, key, and mutable fields. Minor omissions around update behavior when optional fields are absent and return values keep it from being fully complete.

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?

Description adds meaning beyond the schema: name is the identifying key and is case-insensitive, while email/phone are the fields that get updated. The schema already documents the phone E.164 format. With only 33% schema coverage, the description partially compensates but does not explain formats or behavior for email or empty values.

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 operation ('Add a household member or update phone/email') with resource 'member' and clearly distinguishes from read/delete siblings such as get_members and remove_member. The name-key detail further confirms it is an upsert, not a generic update.

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?

Clear context: use this when the member may or may not exist and phone/email need to be set, with name acting as the lookup key. It does not explicitly name alternatives or state when not to use it, but the sibling set makes the choice straightforward.

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