switch

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

With no annotations, the description carries the full disclosure burden and meets it thoroughly: it discloses the side effect of recording rollback_generation first, the 'degraded' status semantics when units newly fail, log-tail trimming on success, and the 'privilege' diagnosis on sudo auth failure. These are exactly the behavioral traits an agent cannot infer 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?

Six sentences, each carrying a distinct fact: purpose, rollback recording, structured summary return, log trimming, degraded status, validation behavior, and privilege error handling. There is no filler and no repetition of schema defaults, making the density of useful information exceptionally high.

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?

Given an output schema exists, the detailed return-format description is a bonus rather than a necessity, and the description covers side effects, status semantics, validation behavior, and error edge cases. The main gap is flake_uri, whose interaction with mode (e.g., which flake to activate from) is undocumented in both schema and description. Slightly less complete than the rest of the definition.

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 0%, so the description must compensate — and it does for three of four parameters: full_log (tail trimmed unless True), validate (gates on check('dry-build')), and mode (via the nixos-rebuild vs home-manager switch pairing). However, flake_uri is never mentioned, leaving its semantics entirely to inference. This is strong partial compensation for a fully undocumented schema.

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 opening verb 'Activate' names the precise operation — deploying the configuration as the active generation — and the parenthetical '(sudo -n nixos-rebuild switch / home-manager switch)' pins down the exact underlying commands. This clearly differentiates it from siblings like build, check, and diff, none of which activate a new generation.

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 gives some routing context by referencing check('dry-build') as the pre-activation validation gate and by implying this is the activation step in a workflow. However, it never explicitly states when to prefer this over build or diff, nor does it give a when-not-to-use condition. Guidance is largely implicit rather than explicit.

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