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

Annotations already declare read-only, idempotent, non-destructive, and no open-world behavior. The description adds useful operational context beyond that: no key is required, and it lists what the response contains (item names, USD prices, buy URLs, pay methods). The return details are somewhat redundant with the output schema, but the auth note and product scope add value.

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 definition is front-loaded with the WHEN clause and sibling differentiation, and it uses labeled fragments effectively. Some content — credit line, contact email, repeated title — is not strictly necessary for invocation, but the overall structure is efficient and scannable.

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 zero parameters, an output schema, and strong annotations, the description supplies everything an agent needs: purpose, alternatives, auth posture, return contents, and an example call. There is no meaningful gap for a simple browse tool.

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 parameter semantics has no substantive burden. The example invocation `arena_db_shop {}` is provided, which is helpful for a no-argument tool. Baseline 4 is appropriate.

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 — browse the Dead Brands Shop — and names the product category (official real-money USD digital products) with examples. It explicitly contrasts itself with Trading Booth, Bazaar, arena_shop_browse, and arena_prize_shelf as Credits-only siblings, so an agent can distinguish it without opening schemas.

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 WHEN line gives the exact condition for using this tool, and the description explicitly names the alternative siblings and the distinction (real money vs play Credits). This is a complete routing instruction with exclusions.

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