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

Annotations declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint=false, which are consistent with a read-only batch query. The description adds context beyond annotations: it notes that unknown players appear in not_found, that IDs must be strings (not numbers to avoid precision loss), and that include fetches FACEIT and bans with one call per batch. These are valuable behavioral details not in 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 a single paragraph of about 5 sentences, front-loading the key efficiency benefit. Every sentence adds value—no fluff. Could be slightly more structured (e.g., bullet points for ID formats), but still concise and informative given the tool's complexity.

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 input schema covers 100% of parameters, 2 simple params, no output schema, and no nested objects, the description is largely complete. It covers usage boundaries (max 100, format rules, exclusion of vanity), behavior for unknown players, and extra include options. Minor gap: no explicit mention of return format or error behavior, but the schema-less output is acceptable here due to complexity.

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?

Despite 100% schema coverage, the description adds significant meaning: it lists all accepted SteamID formats, warns about numeric precision, and explains that not_found indicates unknown players. It also clarifies that `include` adds FACEIT and bans via a single batch call. This exceeds what the schema's brief descriptions provide.

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 'Up to 100 Steam profiles in one call' and emphasizes batch efficiency, which distinguishes it from sibling tools like steam_profile (single player). It uses a specific verb+resource combination and highlights the cost benefit.

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 explicitly advises to always use this tool over per-player calls for multiple players, explains the cost advantage, and warns that vanity names are not supported (delegate to steam_identity). However, it does not explicitly state when NOT to use it (e.g., if only one player is needed, steam_profile may be simpler).

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