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

With no annotations, the description carries the full behavioral burden, and it discloses the tool's read-only nature, the specific metrics returned, the token scope, and that it is free. It does not detail response format or side effects, but for a zero-parameter usage query this is adequate.

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 compact and front-loaded, immediately stating the core purpose, then listing specific returned values, and ending with actionable guidance and cost/scope notes. Every sentence contributes useful information without redundancy.

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 no-parameter, no-output-schema introspection tool, the description is complete: it names all key returned metrics, explains the benefit (self-govern spend), gives usage guidance, and clarifies scope and cost. Nothing critical is missing for an agent to call 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; the schema already fully describes the parameter set as empty. The description adds relevant context about what data the tool reports, though it need not explain any parameters.

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 ('See') and identifies a concrete resource: the caller's current usage and remaining allowance, with a detailed list of returned data (snapbacks, guard checks, estimated spend, % used, reset time). It does not explicitly contrast itself with sibling tools like budget_guard or my_impact, so it falls short of full sibling differentiation.

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?

It gives clear usage context by saying 'Call it periodically to avoid surprises,' which tells the agent when to invoke it. It does not mention alternatives or when not to use it, so it lacks explicit exclusions.

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