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

With annotations already declaring readOnlyHint=true, destructiveHint=false and openWorldHint=false, the description still adds meaningful context: the exact return shape (edit script, insertion/deletion counts, per-operation metadata) and a cost/charging model ($0.005 USDC per successful call, failures free). It does not cover size limits or output ordering, so not a full 5.

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 tight sentences: purpose first, return shape second, pricing third. Every clause (including the pricing/charging rule) carries information an agent would otherwise have to discover by trial.

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 zero-parameter, no-output-schema tool, the description does the heavy lifting on return values and cost. The only gap is that the referenced 'format' parameter is absent from the declared input schema, which could confuse an agent about whether that option is actually accepted.

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?

The schema is an empty object with zero declared parameters (baseline 4), yet the description names a 'format' option with its enum-like value 'unified' and its effect on the response. That is real semantic value the schema does not supply, though the mismatch between a mentioned parameter and an empty schema is a slight inconsistency.

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 ('Line-level LCS diff of two text blobs'), which is unambiguously distinct from all siblings (chunk, dedupe, normalize, validate). An agent can select it without opening the schema.

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?

Usage is implied by the nature of a diff and by the format='unified' mention, but there is no explicit when-to-use or when-not guidance and no named alternative among the sibling tools. Adequate but leaves selection context to inference.

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