list_plans

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

Annotations already declare readOnlyHint: true, so the description does not need to restate safety. It adds useful context by clarifying that 'plans' are 'budgets' and by specifying the returned fields, which goes beyond the bare annotation. No behavioral contradictions exist.

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 a single, front-loaded sentence that states the action, the resource, and the key returned fields. There is no filler or redundant information; every word 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, parameterless list tool, the description is complete: it names the resource, clarifies terminology, and lists the returned fields. The output schema handles the full return structure, and annotations cover the read-only nature. An agent has everything needed to 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, and the input schema is empty with 100% schema description coverage, so there are no parameter semantics to document. The description's mention of output fields is extra and not required. Baseline for zero-parameter tools is 4.

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 uses a specific verb ('List') and identifies the resource as 'plans (budgets)' on the YNAB account. It also names the returned fields (id, name, last month, currency), which clearly distinguishes it from sibling list tools like list_accounts and list_payees. No tautology; an agent immediately knows what this tool does.

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 clearly implies when to use this tool: when you need the budget plans for the current YNAB account. It does not explicitly name alternatives or exclusion criteria, but the distinct resource and simple parameterless nature make the usage context clear. Sibling tools target different entities, so the risk of confusion is low.

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