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

With no annotations, the description carries the disclosure burden and uses it well: it states the operation is unmetered and clarifies a potentially surprising keyless fallback (anonymous unique-per-day remaining, not a wallet). It does not describe the exact response shape, but the key behavioral nuances are surfaced.

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?

Two tightly packed sentences with the main purpose front-loaded and the important edge case in the second sentence. No filler or redundant restatement of the tool name.

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-style tool with no output schema, the description explains the core concept, the wallet timing, and the keyless exception, covering the main sources of confusion. It stops short of stating the exact return representation/type, 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?

There are no parameters and the schema coverage is trivially complete, so there is nothing for the description to add to parameter meanings. The no-parameter baseline of 4 applies, and the API-key/keyless context is useful environmental information.

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?

States a specific verb ('Show'), a specific resource ('remaining Census credits for this API key'), and distinguishes keyed wallet results from anonymous per-day remaining. Clear and distinct from all census_* siblings.

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?

No sibling directly overlaps with credit checking, so no exclusionary routing is necessary. The keyed-vs-keyless distinction gives clear contextual guidance for what to expect, though it does not spell out when to prefer this tool over alternatives.

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