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

Annotations only flag the mutation/open-world/destructive profile; the description goes well beyond that by disclosing asynchronous background execution, credit billing to the organisation, the required edit permission, and a concurrency constraint with retry guidance. These are exactly the operational traits an agent cannot derive from structured fields.

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?

Four short sentences, each carrying distinct information (what it does, how it runs, cost, access, retry condition). The core action is front-loaded and nothing is padded.

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 an async, no-output-schema tool it covers permissions, cost, and concurrency well. The one gap is that it never says how to observe the result of the background run (e.g., via get_chat_result or a status sibling), which an agent invoking a fire-and-forget mutation would benefit from.

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% with only two documented parameters, so the schema already carries the semantics. The description adds only the indirect hint that `message` is a natural-language instruction ('the same as asking in chat'), which is marginal beyond what the schema states.

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 (change an existing site) and frames it as the programmatic equivalent of a chat request. This clearly separates it from create_site, get_site, and list_sites without the agent needing to open any 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?

Gives real preconditions: edit access is required, and if a build is already running the agent should wait and retry. It implies use for modifications to existing sites rather than creation, but never explicitly names create_site or ask_zenning as the alternative path, so routing is left partly to inference.

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