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

Annotations already declare idempotentHint=true, destructiveHint=false, and readOnlyHint=false. The description reinforces idempotency and adds critical side effects: invite emails sent to new entries, the optional message inclusion, and the Pro-plan refusal behavior. It also clarifies that domain entries receive no email. This goes beyond annotations and does not contradict them.

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?

The description is long but every sentence carries information: use cases, behavior, alternatives, prerequisites, plan requirements, and side effects. It front-loads the core purpose before diving into details. No filler or repetition; it is dense but well-structured.

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?

The tool is a write operation with multiple nuances: idempotency, invite emails, plan gating, and a private-site prerequisite. The description covers all of them, plus alternatives. No output schema exists, but for a mutation tool this is acceptable; the description provides everything an agent needs to decide whether and how to call it correctly.

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%, so baseline is 3. The description adds meaning beyond the schema: it explains that `message` is a personal note in the invite email (schema only says optional), that `allowlist` entries are appended and duplicates ignored, and that domain entries don't get emails. It also clarifies the `site_id` must point to a private site. This is useful semantic enrichment.

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: 'Adds email and/or domain entries to a private site's allowlist.' It distinguishes itself from set_allowlist (replace) and remove_from_allowlist (take off), so an agent can tell them apart. The phrase 'WITHOUT removing anyone already on it' makes the scoped behavior unambiguous.

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 explicit triggers ('when the user wants to let one more person in, invite a client, or share it with the team') and names the exact alternatives: 'use `set_allowlist`' for replacement and 'use `remove_from_allowlist`' to remove. It also states the prerequisite (site must be private) and the Pro-plan restriction, leaving no ambiguity about when to invoke.

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