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

Beyond the annotations (idempotentHint, destructiveHint=false), the description adds real behavior: accounts activate immediately, orders are still human-reviewed, resending the same account returns action "unchanged", and sandbox accounts are never invoiced. It omits what delete_missing does and how dry_run behaves, which is the notable gap for a mutation 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?

The content is front-loaded and dense, leading with what the tool declares and then the required provisioning inputs, defaults, and idempotency behavior. The telegraphic 'AdCP sync_accounts:' prefix and semicolon-chained clauses cost a little readability but no sentence is wasted.

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 batch mutation tool with 50-item arrays, no output schema, and 0% schema coverage, the description covers the core account fields well but leaves dry_run, delete_missing, and idempotency_key unexplained, and says nothing about limits or partial failures across the accounts array.

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 0%, so the description carries the burden and partly meets it by explaining brand.domain, operator, billing, payment_terms values (prepay/net_15/net_30, default net_30) and currency USD. However, three of the four top-level parameters (idempotency_key, dry_run, delete_missing) get no semantic explanation, leaving meaningful gaps.

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 a specific verb and resource: declaring or updating the advertiser account you will buy on, with concrete provisioning fields (brand.domain, operator, billing). It is clear what the tool does but never distinguishes it from siblings such as list_accounts, so it stops short of a 5.

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?

Usage is implied rather than stated: you provision an account before buying, and sandbox:true gets a test account. There is no explicit when-to-use/when-not, no mention of checking list_accounts first, and no guidance on delete_missing, so the agent must infer the workflow.

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