tailscale_update_acl

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

The description reveals important behavior beyond annotations: the policy is replaced as a full string to preserve HuJSON formatting, comments, and trailing commas, and the ETag prevents overwriting concurrent changes. This gives the agent a clear mental model of the destructive yet idempotent replace semantics that the annotations alone do not convey.

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 deliver the action, the formatting rationale, the concurrency requirement, and the safe workflow with zero wasted words. The most critical constraint, passing the ETag, is front-loaded.

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 two-parameter update tool with a full input schema and clear annotations, the description covers what matters most: what to pass, why, and the required preceding call. No output schema exists, but return-value details are not essential for a mutating ACL update.

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 coverage is 100%, so the baseline is 3. The description adds meaningful context by explaining why the policy must be the full text and why the ETag is required, enriching both parameters beyond their schema descriptions.

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?

Description opens with 'Update the ACL policy for your tailnet,' a specific verb-plus-resource statement that clearly identifies the operation. It also names tailscale_get_acl as the ETag source, distinguishing this write operation from the read tool without ambiguity.

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 provides an explicit workflow: get the current ACL first, make targeted text edits, and pass the full modified policy back. It clearly states the ETag prerequisite but does not explicitly compare against sibling validation tools like tailscale_validate_acl or tailscale_preview_acl, so it slightly misses the 'when not to use' bar.

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