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

The description goes beyond annotations by disclosing the side effect that 'The segment is converted to STATIC' and clarifying the 'Replace' semantics, which implies existing members are overwritten. Annotations already indicate readOnlyHint=false and idempotentHint=true, so this adds useful context without contradicting them.

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 two sentences, front-loaded with the primary action and side effect. Every word earns its place with no unnecessary detail.

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?

For a simple tool with two fully documented parameters and an output schema, the description covers the essential behavior (replace and convert to static). It does not explicitly mention prerequisites (e.g., segment must exist), but this is implied and not a significant gap. The existence of an output schema covers return value details.

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?

The input schema already provides 100% coverage with descriptions for both segmentId and accountIds ('The segment ID' and 'CRM account IDs to set as segment members'). The description's phrase 'with the given account IDs' adds no new semantic detail beyond what the schema already states.

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 action: 'Replace the members of a STATIC customer segment with the given account IDs.' It uses a specific verb and resource, and notes the conversion to STATIC, which distinguishes it from siblings like update_segment (which likely updates segment properties) and get_segment_members (which reads members).

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 implies usage: it is for setting the full member list of a static segment, and it converts the segment to static. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention any exclusions or alternative tools for adding/removing individual members.

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