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

Annotations already provide readOnlyHint=true, so the read-only nature is covered. The description adds the GET endpoint and the optional zoom behavior, but it does not go much deeper with response format, error cases, or other behavioral details, which keeps this at a solid but not exceptional level.

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?

The description is two short, purposeful sentences. It front-loads the main action and unique selector, then gives the endpoint and zoom behavior; there is no filler or redundant restatement of the title.

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 simple read-only fetch with fully documented parameters and a readOnlyHint annotation, the description covers everything needed to call it correctly: the transaction id, the optional zoom behavior, and the underlying API route. No output schema exists, but 'get a single transaction' sufficiently conveys the expected result.

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% and both id and zoom are documented. The description adds extra concrete examples of zoomable resources (payments, applied_taxes) beyond the schema's 'items,customer', giving the agent more useful value without contradicting 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?

The description clearly states the action ('Get'), the resource ('single transaction'), and the selector ('by id'), which distinguishes it from foxy_list_transactions and other foxy getters. The optional zoom note adds useful scope without blurring the core purpose.

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 description makes the context clear: use this when you have a transaction id and need one transaction, optionally with embedded related resources. It does not explicitly name alternatives like foxy_list_transactions for discovery, so it stops short of a 5, but the intended use is not merely implied.

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