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

Annotations only say readOnly=false, destructive=false, openWorld=false; the description goes much further by disclosing the return artifact (a short-lived, single-use SKULayer URL), the identity requirement (owner signed in as the same person), the token boundary ("You never receive Google tokens"), and the rate limit. It also clarifies the side-effect boundary — no data source added, no writes to Merchant Center — which is not inferable from the non-destructive annotation alone.

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-loads the action and the returned URL, then layers the conditional feedId path, the multi-account fallback, and the hard constraints in descending order of importance. Dense but every sentence carries distinct operational information; nothing is repeated from the schema or annotations.

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?

No output schema exists, and the description compensates fully by describing the returned URL and its single-use, short-lived nature plus the redirect to Google consent. For a single optional parameter with a follow-up flow, an agent has everything needed to call it and to handle both the one-account and many-account outcomes.

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; the description adds real semantics by explaining the conditional nature of feedId (attaches the feed only when Google shows exactly one account) and describing the branch when multiple accounts exist. The schema already covers the omit case, so the marginal gain is modest rather than transformative.

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 ("Start connecting Google Merchant Center for this workspace") and immediately distinguishes the tool from siblings by naming get_merchant_link and select_merchant_account as the follow-up path. It also carves out explicit non-scope ("does not add a data source and does not write to Merchant Center"), so the agent can tell exactly what this call achieves.

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 a clear when-to-use and a full branch plan: owner-only initiation, poll get_merchant_link and call select_merchant_account when several accounts appear. Constraints are explicit (owner only, 5 starts per workspace per hour on top of the normal MCP limit), which is exactly the routing information an agent needs before invoking.

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