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

Annotations only declare readOnlyHint=false and destructiveHint=false, so the description carries most of the behavioral load: it discloses the auth requirement, that the invite is single-use, and what the member does with the delivered links. It does not say whether an existing member can be re-invited, whether the invite expires, or whether prior invites are invalidated.

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?

Front-loads the core action and return payload, then separates access/auth requirements into a clearly marked block. Every sentence carries distinct information with no redundancy.

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?

With no output schema and minimal annotations, the description compensates by describing the returned deep links and QR code and by spelling out the authentication flow needed before calling. An agent has enough to call it correctly on the first attempt.

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% (both id and member_id are documented with format patterns), so the baseline is 3. The description adds no syntax, format, or semantic detail beyond what the schema already provides.

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 ('Mint a single-use enrollment invite for a Circle member') plus the resulting artifacts (Telegram/WhatsApp deep links, QR code) and the member-side action. This is clearly distinguishable from the sibling add_circle_member and add_circle_member_channel, which mutate membership/channels rather than producing an invitation artifact.

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 an explicit prerequisite ('needs a Proof account', authenticate first) and a pointed exclusion ('start_login does NOT open this tool'), which prevents a common misuse path. It stops short of naming add_circle_member as the alternative when the member should be added directly rather than invited.

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