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

Annotations already declare the tool read-only and non-destructive. The description adds useful behavioral context: the user may belong to multiple companies, and any company switching must happen through the authenticated client/session rather than through a model-visible tool. 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?

Two sentences, each earning its place. The main purpose is front-loaded in the first sentence, and the second sentence provides an important usage constraint without any filler.

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 zero-parameter, read-only listing tool with an output schema, the description is complete. It explains what is listed, who it applies to, and the key switching constraint, so an agent can invoke it correctly without further clarification.

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 tool has zero parameters, so there is nothing to document beyond the schema. The description adds meaningful context about the scope of the result—companies the authenticated user belongs to—which is enough for a parameterless 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 clearly states the tool lists all companies the authenticated user belongs to, using a specific verb and resource. It is clear and distinct from siblings like list_tracks or list_campaigns, but it does not explicitly name or differentiate against a similar sibling.

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?

It provides clear context by noting this is useful for users with multiple label/company accounts. It also explicitly warns that company switching cannot be done through a model-visible tool, giving the agent a when-not-to-use boundary, though it names no alternative tool.

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