get_upgrade_plans

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

The annotation readOnlyHint=true already discloses the read-only nature. The description adds the 'upgrade' context, which is useful, but does not disclose return format, authentication requirements, or any side effects. Since the bar is lower with annotations, this description provides minimal additional behavioral context, warranting a 3.

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?

A single, clear sentence with no redundant words. It is front-loaded with the primary action and object, making it easy to parse. Nothing is wasted.

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 no-parameter read-only list operation, the description is adequate. However, it does not describe the response structure (since there is no output schema) nor clarify how it differs from get_plans or get_renewal_plan. This could confuse an agent about which tool to invoke, so it is not fully complete.

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?

With 0 parameters, the schema already has 100% coverage and no parameters to explain. Per the rubric, baseline for 0 params is 4. The description adds nothing needed for parameters, so this score is appropriate.

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 'List plans the account can upgrade to' clearly identifies the verb (list) and resource (upgrade plans), and distinguishes itself from siblings like get_plans (all plans) and get_renewal_plan (current plan) by focusing on upgrade eligibility. It is specific but does not explicitly name alternatives, so it is not a perfect 5.

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 implies usage for upgrade scenarios but does not explicitly state when to use this tool versus get_plans or get_renewal_plan. There is no exclusion or alternative guidance, so an agent must infer context from the word 'upgrade'. This is adequate but not explicit.

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