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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered elsewhere. The description usefully adds that only directly accessible accounts (not the full manager hierarchy) are returned and that output is IDs rather than account objects, but it omits pagination, empty-result behavior and quota/rate considerations; the trailing 'Tools revision' line is metadata, not behavioral signal.

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 core sentence is front-loaded and efficient, and the cross-reference to get_org_context is well placed. However the 'In AdCopilot, ...' phrasing is vague about which agent context applies, and the appended 'Tools revision: d80f65c0.' is pure boilerplate that adds no decision value.

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 an output schema present and annotations covering safety, the description only needs to convey scope and routing, which it does. The remaining gap is minor: an agent cannot tell from the text whether the returned IDs include manager-account descendants or how large the list may be.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. No parameter guidance is missing.

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 first sentence states a specific verb and resource ('Returns ids of customers') and scopes it to accounts 'directly accessible by the user authenticating the call'. This implicitly separates it from hierarchy-wide listing, though it never names a sibling in the negative except by pointing to get_org_context's broader output.

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 a clear fork: this tool for bare IDs, get_org_context when you need the connected accounts plus business profile and next steps. That covers when-to-use and one alternative, but offers no explicit exclusions or prerequisites (e.g. whether it works without an OAuth-connected manager account).

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