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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral context by explicitly stating no execution or network access and describing what analysis is performed. It does not contradict annotations and adds supplementary detail beyond the structured hints.

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 entire description is one focused sentence. It front-loads the core action and constraints, then lists specific outputs without padding. Every phrase contributes meaningful information.

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?

Given the output schema exists, the description does not need to explain return values. It covers the core inputs, the static nature of the operation, and the major output categories. It lacks detail about language/filename parameters and edge-case limitations, but remains largely complete for this tool's complexity.

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. It clarifies that before/after are source snapshots, but it does not explain the filename or language parameters, their defaults, or their impact. Two of four parameters remain underspecified.

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 starts with a specific verb ('Compare') and identifies the resource (caller-supplied before/after source snapshots) and scope (without execution or network access). It lists concrete outputs (source fingerprints, syntax regressions, structural deltas, function-level changes, bounded review findings), which clearly distinguishes it from sibling tools like developer.structured-diff and developer.code-metrics.

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?

It provides clear context: this is a static, non-executing, offline comparison of source snapshots, which implies when to use it (safe code review). It does not explicitly name alternatives or state when not to use it, so it stops short of a 5.

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