RunInstances

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

With no annotations provided, the description carries full burden for behavioral disclosure. It mentions the batch creation capability but doesn't disclose critical behavioral traits: whether this is a destructive/write operation (implied but not stated), what permissions are required, whether there are rate limits, what happens on failure (partial success?), or what the return format looks like. For a complex creation tool with 7 parameters, this is a significant gap.

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 appropriately concise - two sentences that efficiently convey the core purpose and usage scenarios. It's front-loaded with the main action ('批量创建ECS实例') followed by context. There's no wasted verbiage, though it could potentially benefit from slightly more detail 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 this is a complex instance creation tool with 7 parameters, no annotations, and no output schema, the description is insufficiently complete. It doesn't address critical aspects: what the tool returns (instance IDs? status?), error conditions, permissions required, cost implications, or behavioral details like whether instances start automatically after creation. The description should do more to compensate for the lack of structured metadata.

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 100%, so all parameters are documented in the schema. The description doesn't add any parameter-specific information beyond what's already in the schema descriptions. It mentions batch creation which relates to the 'Amount' parameter, but doesn't provide additional context about parameter interactions, dependencies, or usage patterns. Baseline 3 is appropriate when schema does the heavy lifting.

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's purpose: '批量创建ECS实例' (batch create ECS instances). It specifies the verb (create) and resource (ECS instances), and adds context about batch operations. However, it doesn't explicitly differentiate from potential siblings like 'StartInstances' or 'DescribeInstances' beyond mentioning batch creation scenarios.

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 some usage context: '适用于需要同时创建多台ECS实例的场景，例如应用部署和高可用性场景' (suitable for scenarios requiring simultaneous creation of multiple ECS instances, such as application deployment and high availability scenarios). This gives implied guidance about when to use it (batch creation needs), but doesn't explicitly state when NOT to use it or mention alternatives like creating single instances through other means.

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