Diff Text

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description is fully consistent with these. Beyond annotations, the description adds the line-by-line behavior and the +/- marker convention, which tells the agent what output to expect. It doesn't address edge cases (binary input, empty strings, very large texts), but for a read-only diff tool the annotations cover the safety profile and the description adds useful behavioral detail.

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?

Three sentences with zero waste. The core purpose and output format are front-loaded in the first sentence, usage guidance follows, and the web-link reference is brief and optional. 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 simple read-only tool with annotations covering safety and no output schema, the description covers purpose, output format, and usage. The main gap is ignoreWhitespace semantics, which is not explained in either the description or the schema (0% coverage). The web link is a minor addition but not core. Adequate but with one notable gap.

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 must compensate. 'Two texts' maps to the before/after parameters, but the description never mentions ignoreWhitespace, which is the third parameter. The meaning of before/after is reasonably inferable from 'diff of two texts', but the boolean option's behavior (whether whitespace differences are suppressed) is left entirely to the schema, which has no descriptions. Partial compensation for a 3-parameter tool.

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 a specific verb and resource: 'Line-by-line diff of two texts, marking - removed and + added.' It states both the operation and the output format, making the tool's purpose unmistakable. None of the 19 sibling tools perform text diffing, so it is clearly distinguished from alternatives.

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?

'Use it to check exactly what changed between two versions instead of eyeballing them' gives explicit context for when the tool is appropriate. It doesn't name sibling alternatives or state when not to use it, but among siblings (UUIDs, passwords, encoding, JWT, regex) no alternative does diffing, so the guidance is sufficient for routing.

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