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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds only that the wallet is simulated and that a deregistered flag is included, which is largely restated by the output schema. No extra behavioral context (auth expectations, wallet states, staleness) beyond structured fields.

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-loaded with the purpose, then usage, then exclusions, then a zero-arg call example — all in one dense paragraph with no filler. Slightly staccato phrasing ('Differs from…') and the redundant name prefix keep it from a 5.

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?

A read-only, single-optional-param tool with full annotation coverage and an output schema: nothing an agent needs to call it correctly is missing. Purpose, sibling routing, and the zero-argument usage form are all present.

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?

Only one optional parameter, and the schema documents it at 100% coverage ('Your arena key (or send Authorization: Bearer)'). The description contributes nothing about the key, but the 'bazaar_wallet {}' example usefully signals that no arguments are required, matching the schema baseline of 3.

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: checking Bazaar Credits (a simulated marketplace wallet) plus the deregistered flag. It explicitly distinguishes itself from arena_shop/prize shelf, bazaar_my_goods, and bazaar_claim_daily, so an agent can pick it out of a large sibling set without opening a schema.

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:' clause names the exact situation to use it, and two 'Differs from' clauses name the alternatives and the axis of difference (items vs. faucet vs. play credits). Routing information is explicit rather than inferred.

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