list_addon_plans

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

With no annotations provided, the description carries the full burden. It discloses key behavioral traits: it requires an 'add-on service slug' (authentication/input requirement), returns 'detailed plan information' (output behavior), and implies it's a read-only operation (no destructive hints). However, it doesn't mention rate limits, error conditions, or pagination, leaving some gaps.

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 front-loaded with the core purpose, followed by specific use cases and requirements in a bullet-like format. Every sentence earns its place with no redundancy or fluff, making it highly efficient and readable.

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?

Given the tool's moderate complexity (2 parameters, no output schema, no annotations), the description is mostly complete. It covers purpose, usage, and key behaviors, but lacks details on output format variations (implied by the 'json' parameter) and error handling. With no output schema, more guidance on return values would be beneficial.

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 100%, so the schema already fully documents both parameters. The description adds minimal value beyond the schema—it mentions the 'service' parameter requirement but doesn't provide additional context like examples or edge cases. Baseline 3 is appropriate when the schema does the heavy lifting.

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 verb ('List') and resource ('available plans for a specific Heroku add-on service'), distinguishing it from siblings like 'list_addon_services' (which lists services) and 'get_addon_info' (which gets info about a specific add-on). It specifies the exact scope of listing plans for a service.

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 provides three use cases (view all plans, compare pricing, check availability) and states when to use it ('when you need to...'), with no misleading guidance. It doesn't mention alternatives, but given the sibling tools, this is appropriate as no other tool directly lists plans.

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