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

With no annotations, the description carries the full burden. It usefully discloses the return shape (checksum validity, registry match status, registry details), which implies a live registry call, but says nothing about latency, rate limits, authentication, or failure 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?

Two tight sentences with no waste, and the core action is front-loaded ahead of the return description. Slightly terse given the nearby similarly named siblings it could have referenced.

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 single-parameter tool with no output schema, the description adequately explains what comes back. The remaining gap is routing guidance against validate_abn/validate_acn, which matters because the names are easily confused.

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?

Schema description coverage is 100% and there is one parameter, so the baseline is 3. The description adds no formatting guidance (e.g., 11-digit normalization) beyond what the schema already states about accepting spaces and hyphens.

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 (Verify) and resource (ABN) and scope (against the Australian Business Register), which implicitly distinguishes it from a pure checksum validator. However, it never names or contrasts the sibling tools validate_abn or validate_acn, so the agent must infer the difference.

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?

Usage is only implied: the phrase 'against the Australian Business Register' suggests an external registry lookup, hinting at when this is preferred over a local validation. There is no explicit when-to-use, when-not, or named alternative despite two closely related siblings.

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