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

Annotations already mark this as non-read-only, non-destructive, and closed-world. The description adds important context: Owner-only access, the account must be one Google actually showed, and it does not write a feed or data source to Google. It does not describe persistence or reversibility, but the added constraints are meaningful.

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?

It is short and front-loaded, with each sentence adding useful trigger, parameter-source, validation, permission, or scope information. There is no filler.

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 three-parameter local selection tool with full schema coverage and annotations, it supplies the trigger, required ID sources, authorization restriction, account validation, and non-write scope. No output schema exists, so return-value explanation is not required.

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 schema already defines all three parameters. The description still adds value by linking connectionId and accountId to get_merchant_link and adding the validation constraint that the account must be one Google showed for the connection.

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 states a specific action and resource: choosing which Merchant Center account a feed uses. It also ties the tool to get_merchant_link, making it distinguishable from siblings like listing links or starting a link.

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 an explicit trigger: required when get_merchant_link lists more than one account, and the IDs must come from that result. It does not explicitly name alternatives or state the one-account case, so it falls short of full when/when-not/alternative guidance.

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