tailscale_preview_acl

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds the 'Preview' context, confirming it is a safe, non-modifying operation. It does not disclose additional behaviors like rate limits, response format, or any prerequisites. Since annotations cover the key safety profile, the description does not need to repeat them, but it adds limited new behavioral context beyond the annotations.

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 a single sentence of 20 words, front-loading the key action 'Preview the ACL rules'. No extraneous information. Every word earns its place.

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 has 3 required parameters with full schema descriptions and annotations that cover safety. However, there is no output schema, and the description does not hint at what the response contains (e.g., a list of rules or a summary). For a preview tool, mentioning the return format would improve completeness. Given the simplicity and available metadata, the description is adequate but leaves a gap.

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 input schema has 100% coverage with each parameter described. The description adds value by linking parameters to the preview context: 'specific user or IP address' relates to previewFor, and 'proposed policy' relates to policy. It also clarifies the enum for 'type' by mentioning user and IP address. This contextual meaning goes beyond the schema descriptions, justifying a score above the baseline of 3.

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 clearly states the tool's purpose: previewing ACL rules that would apply to a specific user or IP address under a proposed policy. It uses a specific verb ('Preview') and identifies the resource ('ACL rules') and scope ('specific user or IP address'). This distinguishes it from sibling tools like tailscale_get_acl (get current ACL) and tailscale_validate_acl (validate whole policy).

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 description implies when to use this tool: to see rules for a specific entity under a proposed policy. It provides clear context but does not explicitly exclude cases or mention alternatives such as tailscale_validate_acl for whole-policy validation. The absence of explicit 'when-not-to-use' guidance prevents a perfect score.

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