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

With no annotations provided, the description carries the full burden. It discloses the paid nature (~$0.01 per query), the no-access-token behavior, the response behavior when payment_proof is omitted, and the rationale for historical data ('Storefronts publish today's price and no history, so this exists only because we recorded it'). This goes well beyond a basic read operation. No contradiction with annotations.

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 front-loaded with the use case and is long but every sentence adds value: use cases, data freshness warning, return contents, identifier types, regions, payment, and alternative tools. It is efficiently structured with no filler.

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?

Given the tool has 8 parameters, no output schema, and no annotations, the description is remarkably complete. It covers all key behaviors, return data elements, regions, payment requirements, and how to handle the no-payment case. It also explains the history data provenance, which is essential context for trusting the 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 coverage is 100%, so baseline is 3. The description adds meaning beyond the schema by explaining the accepted identifier types ('Accepts a slug from lookup_game, a Steam appid, a GOG or Epic id, or free text via q') and by describing the payment_proof behavior. This helps the agent choose the right parameter for the input available.

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 tool returns current prices across Steam, Epic, GOG, and Microsoft Store plus historical low price data, with an explicit trigger: 'USE THIS when asked what a game costs...' It distinguishes itself from get_free_games by noting it issues no access token. This is a specific verb+resource with clear scope.

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?

It provides explicit when-to-use guidance: when asked about game cost, cheapness, buy/wait decisions, or cross-store price comparisons. It warns not to answer from memory because prices change daily. It names get_free_games as the alternative and explains the difference, and explains how to handle missing payment_proof ('receive payment instructions rather than an error').

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