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

Adds side-effect context beyond annotations: it initializes a storefront, runs tools/list expecting 6, issues a quote that is 'voided at once, no payment', sends a signed webhook ping, and checks for a PAID test order. This explains why readOnlyHint=false despite being a check. It does not state auth requirements or rate/cost limits.

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 purpose but crams the five sub-steps, the return contract, and the public twin into a single dense run-on with semicolons. Information is earned, but the structure could be broken up for faster scanning.

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-param diagnostic with an output schema, the description covers the action, the internal steps, the return statuses (connected|incomplete with per-step ok|fail|skipped and a code), and points to the public twin. Nothing needed to invoke it correctly is missing.

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?

Zero parameters, so there is nothing to disambiguate; baseline 4 applies. The 'any valid key' phrasing hints at authentication handling but no parameters exist to clarify.

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+resource ('connection check for your merchant') and then enumerates the exact composite steps performed, so an agent knows precisely what happens without opening the tool. It is distinguishable from write-oriented siblings like shop.merchant.register or shop.merchant.rotate_key.

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 parenthetical '(any valid key)' implies this is a diagnostic verifying credentials, but the description never states when to run it versus sibling setup tools (register, accept_terms) or what to do with the result. Usage is implied, not explicit.

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