Preview ACL rules

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description does add one meaningful behavioral fact — that nothing is actually applied, the result is a hypothetical preview — but says nothing about required permissions or what the preview returns.

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?

A single sentence with zero filler, and the key framing (hypothetical preview) is front-loaded. Nothing could be cut without losing meaning.

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 preview/analysis tool the return value is the entire deliverable, yet there is no output schema and the description does not indicate what the preview contains (e.g., matched rules, allow/deny verdicts). What is present is accurate and sufficient to invoke the tool, but thin on outcome.

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% and the enum values for 'type' are already documented in the schema, so the description's mention of 'a specific user or IP address' only restates the schema's two modes. Baseline 3 is appropriate when the schema carries the parameter burden.

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 states a specific verb ('Preview') and resource ('ACL rules'), plus the exact scope: results for a given user or IP under a proposed policy. It is clearly distinguishable from get_acl (current state) and validate_acl (syntax check) by implication, though it never names those siblings outright.

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?

The hypothetical framing ('if a proposed policy were applied') implies when you'd reach for this tool, but there is no explicit guidance on when to use it versus tailscale_validate_acl or tailscale_diff_acl_access, which are the nearest alternatives. Usage is inferable rather than stated.

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