list_account_summaries

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results are scoped to accessible accounts and include property summaries, but says nothing about volume, pagination, or ordering of a potentially large account list.

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?

Two short sentences, zero filler, with the action and scope front-loaded and the usage hint second. Every sentence earns its place.

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, return-value detail is not required, and annotations cover the read-only nature. The description supplies the entry-point role and the IDs it yields, which is what an agent needs; only edge cases like empty access or result size are unaddressed.

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 clarify; baseline for a no-parameter tool applies. The description correctly implies a full unfiltered enumeration of accessible accounts.

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 ('List every GA4 account') plus the payload ('with a summary of its properties'), scoping it to accounts the caller can access. This distinguishes it from list_properties/get_property siblings, which operate on properties rather than the account roll-up.

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?

'Start here to find the account_id and property_id the other tools need' gives explicit entry-point guidance and states why an agent would call it before other tools. It does not name a specific alternative to avoid, but the routing intent is unambiguous.

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