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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description does not contradict them. However, the description adds no behavioral context beyond the conversion—no error handling, response format, or API specifics. With annotations present, the safety profile is covered, but the description itself is thin.

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 extremely concise with a clear arrow notation, containing no filler. However, the brevity verges on cryptic—it could be slightly expanded without losing efficiency, so it earns a 4 rather than 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?

Despite having annotations and an output schema, the description is incomplete. It doesn't provide usage context, input formatting guidance, or behavior for invalid/unknown vanity URLs. The presence of a sibling resolve_entity tool makes differentiation even more necessary, which the description fails to address.

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 0%, so the description must carry the burden of explaining parameters. 'Vanity URL' identifies the input type, but it doesn't clarify whether to provide the full URL or just the custom name, nor any format constraints. The schema example helps, but the description itself provides minimal semantic detail.

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 'Vanity URL → SteamID64' clearly specifies the transformation the tool performs, identifying both input and output. It distinguishes itself from sibling tools like resolve_entity by focusing on the vanity URL to SteamID64 mapping.

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 provides no guidance on when to use this tool versus alternatives such as resolve_entity. There is no mention of prerequisites, exclusions, or contextual scenarios, leaving the agent to infer usage from the name alone.

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