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

With no annotations, the description carries the full burden and does well: it discloses the algorithm (LCS), that output is unified-diff style, that the result is deterministic, and even the cost model ($0.01/call, USDC, eip155:8453). It stops short of stating input size limits, rate limits, or auth requirements beyond payment.

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 purpose and differentiation are front-loaded, which is good, but the third sentence ('Use this when an agent needs to exact line-level diff with unified-style output') largely restates sentence one and is grammatically awkward, so not every sentence earns its place.

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 pure-function text tool with three fully documented required params and no output schema, the description covers the essentials, including the return format (unified-diff style) that the missing output schema would otherwise have to explain. Only edge-case behavior (large inputs, encoding) is unaddressed.

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%, so a/b/context are already documented in the schema. The description mentions 'context' only in passing as part of the output and adds no format, range, or default detail for any parameter, so it does not meaningfully exceed the schema's baseline.

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 and resource ('Compare two texts line by line'), names the algorithm (LCS diff), and specifies the output shape (unified-diff style with exact additions, removals and context). An agent can tell at a glance this is a deterministic text-diffing utility, clearly distinct from siblings like dev_text_chunker or dev_text_extract.

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?

Provides a clear when-to-use trigger: 'Use this when an agent needs a line-level diff with unified-style output.' It also implicitly contrasts with the alternative of asking a model to find differences ('Deterministic, unlike...'). However, it names no sibling tool and gives no when-not-to-use or input-size caveats.

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