tailscale_update_device_key

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

Annotations already indicate the tool is not read-only, not destructive, and idempotent. The description adds context about disabling key expiry for servers, which aligns with these hints. However, it doesn't disclose potential side effects (e.g., impact on existing sessions) beyond what is inferred from the schema.

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?

Two concise sentences: first states the purpose, second provides a practical example. No unnecessary words, and the key information 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 simple two-parameter boolean update without an output schema, the description and schema together provide sufficient context. It could mention re-enabling key expiry, but the example and param names implicitly cover it.

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%, and both parameters have clear descriptions in the schema. The description echoes 'disabling key expiry' but adds no new semantic information beyond the schema. Thus, it meets the baseline for high coverage.

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 it updates device key settings, specifically disabling key expiry, which distinguishes it from sibling tools like tailscale_rename_device or tailscale_expire_device. The verb 'Update' and resource 'device's key settings' are specific and 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?

The description provides a concrete use case: 'Useful for servers that should never need to re-authenticate.' This implies when to use the tool. However, it does not explicitly mention when not to use it or differentiate from sibling tailscale_update_key (which deals with auth keys), leaving slight room for confusion.

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