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

Annotations supply only destructiveHint=true, and the description adds the underlying REST call (POST /tailnet/{tailnet}/keys) without contradicting them. It does not disclose the practically important traits of a key-creation call: that the key secret is typically shown only once, the OAuth scope required, or rate limits. Useful but thin given annotations cover little.

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 short sentences, front-loaded with the action and resource, and the REST endpoint is tucked at the end. No filler and nothing redundant.

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 six-parameter mutation tool with no output schema, the description covers the what but omits the critical return behavior — the newly minted key/secret — as well as permission prerequisites. Since no output schema exists, the description is the only place that could explain what the caller receives.

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%, with all six parameters (tags, reusable, ephemeral, description, expirySeconds, preauthorized) documented in the schema itself, so the baseline is 3. The description adds no parameter syntax, defaults, or interaction detail beyond what the schema already provides.

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?

States a specific verb and resource ('Create a new auth key for the tailnet') and adds the business purpose (registering new devices). It is clearly distinguishable from list_keys/get_key/delete_key siblings by verb, though it never names a sibling it is not.

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?

There is no when-to-use vs when-not guidance. The parenthetical 'used to register new devices' hints at context but does not route the agent among alternatives such as list_keys (to inspect existing keys) or delete_key/expire_device_key.

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