setup_add_account

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

With no annotations, the description carries the full burden and does well: it discloses the interactive two-call handshake, what the first call returns (a consent URL), and a genuine side effect — that all Google tools then require email on every call. It stops short of stating permission scopes, token persistence, or what happens if the consent URL is never completed.

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?

Three sentences, zero filler, ordered by the sequence an agent will actually execute. The downstream email requirement is placed last where it reads as a consequence rather than competing with the core instruction.

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 zero-required-param, no-output-schema setup tool, the description covers the flow, the return value of step one, and the cross-tool consequence. Only failure/abort behavior and account-limit details are absent, which are minor for this operation.

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 coverage is 100%, so the baseline is 3, and the description adds real value by clarifying the state-dependent meaning of url_or_code (omit to start, pass localhost URL or bare code to finish) and noting email's preselect/verify role. This is more than a restatement of the schema.

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?

Specific verb+resource ('Authorize an additional Google account') with a clear scope qualifier ('additional') that separates it from setup_auth and setup_list_accounts, which are the nearest siblings. An agent can pick this tool without opening the schema.

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?

The two-phase usage is spelled out precisely: call without url_or_code to obtain a consent URL, then call again with the post-consent localhost URL/code. The word 'additional' implies setup_auth handles the first account, but the alternative is never explicitly named and no when-not-to-use condition is given.

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