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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds genuinely useful context beyond that — the 'Contains personal data' PII warning and the underlying GET /transactions/{transaction_id} endpoint mapping — but says nothing about not-found behavior, errors, or response shape.

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?

Three short, front-loaded sentences with the resource, the expansion options and the PII caveat each given a clause. The trailing endpoint reference is mildly redundant but cheap and aids API cross-referencing.

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?

With no output schema, the description carries the burden of describing returns. It names the expansions but not the shape of the returned transaction, nor behavior for missing/invalid IDs, leaving a moderate gap for a single-fetch tool flagged as containing personal data.

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 description coverage is 100%, so all four parameters are documented in the schema itself, including the ID's string-or-integer union and pattern. The description only restates the flags collectively as 'optionally with line items, discounts and payments' and adds no format or default semantics on top of the schema — baseline 3 applies.

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 — fetch a single transaction (receipt) by transactionHeadId — and enumerates the optional expansions (line items, discounts, payments). The singular/plural contrast with smaregi_list_transactions is implicit rather than named, so it stops short of explicit sibling differentiation.

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?

Usage is only implied: 'by its transaction id' signals that an ID must already be known, which indirectly points to the list tool for discovery. There is no explicit when-to-use/when-not guidance, no mention of what to do if the ID is unknown, and no prerequisite statements.

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