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

Annotations only say this is a non-destructive, non-idempotent write; the description goes much further by disclosing the per-organisation daily quota, that nothing is scanned server-side, that a banner build is queued, and that other tools will keep using the default domain afterwards. These are exactly the operational facts an agent needs before invoking a mutating tool.

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 sentences, front-loaded with the action and side effect, then quota and workflow caveats — no filler. Slightly dense, but each sentence carries distinct information.

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 single-parameter mutation with annotations and an output schema, the description covers the important unknowns: quota limits, server-side non-action, queued banner build, and default-domain behaviour of siblings. Nothing an agent needs in order to call it correctly is missing.

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 schema already documents URL normalization, leading-www stripping and port refusal. The description adds no additional meaning about the 'domain' argument beyond calling it a 'website domain', so the baseline of 3 applies.

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 opens with a specific verb and resource — 'Adds a website domain to the connected CookiePal account' — plus the immediate side effect of queueing a banner build. This clearly separates it from read-only siblings such as list_domains and whoami, so an agent can pick it without inspecting schemas.

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 real usage context: the tool is for the free plan, applies the same checks as the dashboard, and is capped at 10 domains per organisation per day. It also explains the downstream workflow ('the result says how to run the first scan on the user's computer') and the cross-tool default-domain caveat, though it never names start_scan or list_domains as explicit next/alternative calls.

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