Update flag environment config

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

Annotations already declare destructiveHint: true, so the safety bar is covered. The description adds valuable behavioral details: defaultVariationId is 'required by the API', only SingleVariation is currently supported at environment level, and prerequisites have an 'omit to leave untouched / pass list to replace wholesale' semantic. 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 a single efficient sentence that front-loads the purpose, then packs the field semantics into a parenthetical list. Nothing is redundant, though the density slightly hurts readability. It earns its place.

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 destructive operation with six parameters and no output schema, the description covers the key fields but leaves gaps: it doesn't state what happens if strategy is omitted (presumably unchanged, but not stated), nor does it clarify how project/flag/environment should be identified (key vs ID). An agent may need to consult sibling tools or schemas for these 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?

Schema description coverage is low (33%), so the description must compensate. It does explain defaultVariationId (served on fallthrough, required), strategy (enum values and current limitation), and prerequisites (omit vs replace). However, it provides no meaning for project, flag, or environment identifiers, which are equally necessary to invoke the tool.

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 opens with a specific verb and resource scope: 'Update a flag's per-environment serving config'. It enumerates the exact fields affected (defaultVariationId, strategy, prerequisites) and explicitly routes percentage rollouts to update_targeting, making it easy to distinguish from that sibling and from the broader update_flag tool.

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 tells the agent when not to use this tool: 'Percentage rollouts are configured on targeting rules via update_targeting.' This is a clear alternative. It doesn't mention when to use this vs update_flag, but the 'per-environment' scope and the listed fields provide enough contextual guidance.

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