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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real value beyond that: what each account row contains (ID, name, test flag) and the dependency on the merchant.account_id config setting.

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?

Front-loaded with the primary purpose, then return shape, then the config/downstream caveat. Every sentence earns its place; the trailing Merchant API link is the only marginally expendable element.

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 parameterless read tool with an output schema, the description covers everything needed: purpose, platform scope, the account_id linkage to get_merchant_feed_health, and the config condition that makes it unnecessary.

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?

There are zero parameters, so the baseline of 4 applies. The description correctly describes no inputs, and its mention of the account_id output clarifies the downstream consumption rather than introducing parameter ambiguity.

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 (List) and resource (Google Merchant Center accounts) with scope ('the connected user can access'). It clearly separates itself from siblings like list_accounts, list_gsc_sites, and list_reddit_accounts by naming the Merchant Center platform.

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?

Gives explicit conditional guidance: it supplies the account_id used by get_merchant_feed_health, but is 'not needed when merchant.account_id is set in the config.' That is a strong when/when-not statement, though it offers no broader alternatives for enumerating accounts.

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