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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false). The description adds genuinely new behavioral context: the call starts asynchronous work, returns only an id, and 'usually takes a few minutes.' It does not state what the id is used for or any cost/rate limits, so it is strong but not complete.

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?

The purpose and the trigger condition are front-loaded, and the async/id/timing note is a tight closing line. The long enumeration of return contents is verbose, but since there is no output schema it earns most of its space.

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?

With no output schema, the description usefully inventories what comes back (score out of 100, verdict, six dimensions, notes, one-line idea, first changes). The one real omission is the async follow-up loop — it says an id is returned but not that the result must be fetched via check_read.

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%, so the baseline is 3. The description still adds meaning by characterizing document_url as 'one document (a pitch deck, memo or product brief)' and framing it as optional relative to the required site, which conveys the intent of the parameter beyond the schema's format list.

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 ('Sigil's review of a company's current brand from its website and, optionally, one document') and clarifies the async model with 'Starts the work and returns an id.' That framing cleanly separates it from the check_read sibling, which is the natural polling counterpart.

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?

'Use it when someone wants feedback on their brand, positioning, messaging, website or visual identity' gives an explicit trigger condition and a concrete list of intents. It stops short of naming check_read as the follow-up step or stating when not to use it, so it is clear context rather than full routing.

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