Get or set the spend limit

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

No annotations are provided, so the description carries the burden. It discloses 'Local-only safety guard, never touches the server', which is a key behavioral trait. It also scopes to this session. However, it does not state whether setting the cap enforces blockages when exceeded or what happens on reset, leaving some behavioral ambiguity.

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 three short sentences, front-loading the most distinctive trait (local-only) and ending with a simple usage tip. No wasted words.

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 two-parameter tool with no output schema, the description is fairly complete: it states the purpose, the local scope, and the read/write semantics. It lacks explicit return-value information and enforcement consequences, but these are not critical for basic usage.

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 input schema already describes both parameters fully (100% coverage), so the baseline is 3. The description adds minimal extra value: it repeats that omitting setUSD checks status, but does not mention reset or provide additional syntax details beyond the schema.

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 states a specific verb-resource pair: 'Reads or sets a USD cap on total spend across all paid r0x tools in this session.' It also adds the unique local-only nature, distinguishing it from server-side tools. This is a clear, specific statement of purpose.

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 gives clear context: it is a local-only safety guard for the session, and explains the read vs. set behavior ('Omit setUSD to just check status'). However, it does not explicitly mention alternatives or when-not to use, though the uniqueness of the tool makes that less necessary.

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