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

With no annotations, the description carries the behavioral burden. It discloses ordering (newest first), version inclusion, and that it returns added/removed entries. This goes beyond the schema, which only describes parameters. However, it omits mention of the 'returned' change type (listed in the schema) and does not describe the output structure, so it is not fully transparent. Score reflects good but incomplete disclosure.

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 two sentences, front-loaded with the core purpose and then a concise differentiator. There is zero waste; every word contributes to understanding what the tool does and why it is unique.

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?

The description lacks an explanation of the 'returned' change value that appears in the schema. It also does not outline what the return items look like beyond mentioning a version. Given the tool's simplicity and optional parameters, this is a moderate gap in completeness, especially for an agent trying to understand all possible change types.

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 coverage is 100%, so each parameter already has a description. The tool description does not add meaning beyond the schema (e.g., it does not explain the 'since' format or the semantics of 'returned'). Since the schema handles parameter documentation, this is a baseline 3.

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 clearly states the tool lists top-level domains added to or removed from IANA's root, newest first, and includes the version. The unique claim 'Nobody else publishes this diff' differentiates it from siblings like get_tld or search_tlds. The verb and resource are specific and unambiguous.

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 implies usage: use this when you need historical TLD change information. The differentiating sentence ('Nobody else publishes this diff') helps an agent know this is the go-to for such data, but it does not explicitly mention when not to use it or name alternative tools. Still, context is clear enough for selection.

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