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

Annotations already declare idempotent=true, destructive=false and openWorld=true, but the description adds context those hints can't carry: the old site stops on "move", sites share one limit, and the token/script tag/claim_url/free words are preserved. It doesn't state the response shape, but for this tool that omission is minor.

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 dense sentences plus a one-clause boundary rule; the primary use case is front-loaded and every sentence carries operational information. Nothing is padding.

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 3-parameter mutation tool with no output schema, the description covers motive, both action semantics, shared-limit behavior, and the localhost alternative. It could mention the cap interaction or what comes back after the change, but an agent has enough to invoke it correctly.

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% and the enum values for action already document "move" vs "add" (including the up-to-3 cap). The description reinforces when each action applies but adds no format or syntax detail the schema lacks, so the baseline 3 is correct.

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 names the resource (the trial's site) and the two distinct operations ("move" replaces it, "add" extends it), each with its effect spelled out. An agent can distinguish this from proxylang_start or proxylang_status without opening the schema.

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?

It gives explicit triggering conditions for both actions (wrong website -> move; test/staging site -> add) and an explicit exclusion with a named alternative ("Not needed for localhost: use localhost_script_tag"). When, when-not, and the alternative are all stated.

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