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

With no annotations, the description carries the burden and does so well: it discloses that this tool returns no figure, that taxation is per-Authority and ad valorem, and that the real fee is reported at transaction time. This prevents an agent from expecting a numeric rate despite the tool's name, though it says nothing about auth or rate limits.

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?

It is front-loaded with the key fact that no network-wide rate exists, then explains the tool's role and the alternative. Slightly stylized prose ('docent', 'Oracle deliberately quotes none') adds flavor but the core information stays tight for a zero-param tool.

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?

An output schema exists, so return contents needn't be described, and with no parameters and no annotations the description covers everything an agent needs to call it correctly. The only gap is sibling-level differentiation among the other explanatory tools.

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 takes zero parameters, so there is nothing for the description to disambiguate; the 4 baseline applies. The text correctly implies no inputs are needed to get the model explanation.

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 role: it explains how Tollbooth certification taxation works and is explicitly 'a docent' that points to the live source. It also warns the agent that no single rate exists, which corrects the potentially misleading name 'get_tax_rate'. It differentiates from the live-figure path (check_price) but not from model-explaining siblings like economic_model or get_rulebook.

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 when-to-use (explain the taxation model) and routes the agent to the explicit alternative for a concrete number — query the relevant Authority's check_price for certify_credits. It stops short of stating when this tool should be preferred over the other explainer-style siblings.

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