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

Beyond the readOnly/idempotent annotations, the description discloses how the check works (factory registration and bytecode absence), why it cannot be spoofed (chain-native precompile authority), and what verdicts it returns (genuine / fake_lookalike / not_b20). This gives the agent a clear mental model of the tool's behavior.

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 essential content is front-loaded and the threat-model explanation is useful, but the later pricing and marketing sentences ('The 2-cent check,' prepaid header, free call/day, no wallet/API key) go beyond the core definition. It is not bloated, but it is longer than a strictly concise tool description needs to be.

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?

Given a single parameter, a present output schema, and strong annotations, the description adds is the missing context: why the check matters, what authority it relies on, what verdicts to expect, and how access/cost works. Nothing critical for calling the tool correctly is missing.

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 single address parameter is already fully described in the schema as 'Token address,' so the description has little additional semantic burden. It only repeats 'Required input: address' and does not add format, chain, or constraint details, making baseline 3 appropriate.

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 opens with the precise question 'Is this a REAL B20 — or a lookalike contract?' and then states the concrete verification: 'factory registration + bytecode absence.' It clearly identifies the tool as the authenticity gate for B20 tokens, and the mechanism distinguishes it from other B20 tools like b20_info or b20_access_type.

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 explicitly commands 'Run FIRST on any B20' and says it 'keeps every other B20 answer honest,' making the when-to-use decision unambiguous: this tool precedes all other B20 analyses. No alternative is named because this is the designated first-step authenticity check.

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