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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is covered. The description adds genuinely new behavioral information beyond that: the tool performs no action ("opens nothing by itself"), what it returns (screens, buttons, fields), and the fact that no public API exists, which explains why a browser-based follow-up is required. It stops short of describing the exact response format or how the steps are structured.

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 action and the key caveat, with no filler. The trailing API note is relevant but awkwardly phrased ("Paperless Post's official API: Paperless Post has no public API (checked 10 Oct 2026)"), and the dated check adds noise an agent does not need.

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 zero-parameter, no-output-schema guidance tool, the definition covers what it returns, that it has no side effects, and the follow-up path via browser tools. The only real gap is that it never says what happens on failure or how the returned steps are scoped, which is minor for this complexity level.

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?

The tool takes zero parameters and the schema is closed and fully described, so there is nothing for the description to disambiguate. Baseline 4 applies; no parameter-level meaning is missing or contradicted.

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?

The description names a specific verb and resource ("Message guests in the user's own Paperless Post account") and then reveals the actual mechanism — it returns a step-by-step walkthrough rather than performing the action. That second sentence is what makes the tool distinguishable, though the framing means an agent must read past the first sentence to learn the tool is a guide, not an executor.

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?

It gives clear usage context: call this to get the Paperless Post steps, then carry them out with the cotlet_browser_* tools in the user's Cloud Browser. It does not name exclusions or contrast with named siblings such as paperless_post_send_invitation, so an agent must infer which of the Paperless Post tools actually performs the send.

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