Signed-in Google accounts

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint), so the bar is lower. The description adds real behavioral context beyond them: the output determines account resolution for every other tool, and the account argument is the switching mechanism. It does not describe the return shape, but that is a minor omission for a read-only 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 tight sentences with no filler. The identity of the tool comes first, followed immediately by the actionable detail about the default account and how to switch.

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?

Given zero parameters, no output schema, and annotations that already declare the read-only, idempotent nature, the description covers everything needed to select and invoke it. The only gap is that the exact return shape (e.g., a list of emails plus a default marker) is left implicit.

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 the baseline is 4. The description's mention of the `account` argument is a cross-tool usage note rather than a parameter of this tool, but it is still helpful context about how the listed emails get consumed.

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 the Google accounts this server can act as') and goes further by naming the second piece of information returned: which account is the default. This is unambiguous and clearly distinct from every sibling tool, all of which operate on sites/sitemaps/analytics rather than accounts.

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?

Explains the context for calling it (to learn the available accounts and the default) and routes the agent to the alternative action: 'Pass an email as the `account` argument on any other tool to switch.' No explicit when-not-to-use case is given, but the cross-tool relationship is spelled out.

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