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

With no annotations, the description carries the full behavioral burden; it does disclose the return shape (diff lines tagged same/add/del plus counts), which is genuinely useful for a pure-computation tool. However it omits any limits (max text size, line count), and says nothing about what the `locale` option changes, leaving gaps.

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 short sentences with no waste; the core purpose is front-loaded and the input/output facts follow immediately.

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?

There is no output schema, so describing the return value here is the right call and it is done adequately. But an unexplained third parameter and absent size/limit guidance leave the agent with open questions for anything beyond the trivial case.

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 0%, so the description should compensate. It names `a` and `b` but only restates their obvious role as the two texts, and it completely ignores the `locale` parameter, which has an enum and a default and is the one parameter whose meaning is non-obvious.

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 ('Compute') and resource ('line diff') plus the scope ('between two texts'). No sibling tool overlaps with diffing, so no differentiation is needed and the purpose is 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 never says when to use this tool versus an alternative, nor any precondition such as input size or encoding expectations. Usage is only inferable from the name.

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