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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It implies a read-only status check by listing return values, but it never explicitly states that the tool has no side effects, requires no parameters, or what happens on failure. The behavioral surface is minimal but not explicitly disclosed.

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 compact sentence that immediately lists the three things the tool returns: balance, spend, and caps. Every word earns its place, and it is front-loaded with the most important information.

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 informational tool, the description covers the essential return categories. It doesn't define 'caps' or specify units/currency, but given the low complexity and absence of an output schema, the description is largely sufficient for an agent to know what it will get.

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 per the rubric the baseline is 4. The description adds no parameter-specific meaning because there are no parameters to describe. Nothing is missing on this dimension.

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 title clearly states 'Show balance and caps' and the description enumerates the specific data returned: prepaid balance, today's spend, and this key's caps. While there is no explicit verb in the description, the resource and scope are unmistakable. It does not explicitly distinguish itself from siblings, but its topic (balance/caps) is unique among 'call', 'describe', and 'search'.

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 provides no guidance on when to use this tool versus the sibling tools. There are no conditions, exclusions, or references to alternatives. An agent must infer that 'balance' is the right choice when balance information is needed, with no help from the description.

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