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

Beyond the annotations, the description adds meaningful behavioral detail: duplicate names fail with a 409 DUPLICATE_NAME error and organizations are limited to 50 sets. This warns the agent about realistic failure modes and constraints without contradicting the write-oriented readOnlyHint=false annotation.

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?

Three short sentences cover definition, constraints, and usage trigger with no filler. The most important information is front-loaded, and every sentence 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 simple create operation with two required parameters and no output schema, the description covers purpose, constraints, and failure behavior sufficiently. It does not describe the return value, but this is mitigated by the schema coverage and the tool's straightforward nature.

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 coverage is 100%, so both parameters are already documented. The description adds extra context for 'name' by noting uniqueness per organization, and frames 'channelIds' as the group of channels being saved for one-click targeting, which reinforces the intent behind the parameter values.

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 clear verb and object: 'Create a channel set,' and immediately defines what a channel set is ('a saved channel grouping for one-click multi-channel targeting'). This makes the tool's role obvious and distinguishes it from sibling tools like list_channel_sets, update_channel_set, and delete_channel_set without needing to open the schema.

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 includes an explicit 'Use this when the user wants to save a group of channels for one-click targeting,' which gives a clear trigger condition. It does not explicitly contrast it with update_channel_set or list_channel_sets, but the creation intent is unambiguous.

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