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 determinism and the x402 payment requirement ($0.006), which is real behavioral context, but it omits the 200k-char input cap, offline/read-only nature, and any rate 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?

Three short, front-loaded sentences covering capability, output, and price with zero filler. Each 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?

The description partially covers returns ('structured ops plus a one-line delta summary') with no output schema, but given 0% schema coverage and an opaque 'options' object, it leaves the mode-selection mechanism and size limits unexplained.

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% and the mode (line/word/char) is mentioned without mapping to any parameter. The 'options' object is documented nowhere in schema or description, so the agent cannot know how to select diff granularity. 'a' and 'b' are self-evident only from the schema itself.

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 (diff) plus the three granularities (line/word/char) and output shape, so the agent knows exactly what it does. No sibling tool performs diffing, so explicit differentiation isn't needed, but it never names an alternative either.

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?

There is no when-to-use guidance: nothing says when a line diff is preferable to a word or char diff, nor how to trigger each mode. The agent must infer mode selection from the 'options' black box with no help.

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