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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds context about the authenticated account scope and explicitly rules out side effects like creating sessions or charging, which reinforces safety expectations. It doesn't describe output format, but this is a simple status check with no output schema.

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-loading the action and purpose, then adding the read-only clarification. Every sentence earns its place with no redundant or filler content.

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 parameterless tool with no output schema, the description is complete: it states the target account, the specific aspects checked (subscription, payment state, Stripe readiness), and the read-only behavior. An agent has enough information to select and invoke it correctly.

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 the baseline is 4. There is no parameter meaning to add; the description focuses on what the tool checks rather than inputs, which is appropriate 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 identifies a specific verb and resource: 'Check the authenticated AgentMart account's Growth Pilot subscription, payment state, and Stripe readiness.' It distinguishes this from siblings like create_checkout and create_billing_portal by focusing on read-only status inquiry rather than creating sessions or charges.

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?

Explicitly states when to use the tool: 'Use for questions about whether billing is active, past due, canceled, or ready.' It also clarifies what it does not do: 'does not create a session or charge anyone.' It stops short of naming alternative sibling tools, but the usage conditions are clearly defined.

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