td_variant_diff

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

With no annotations, the description carries the full burden of behavioral disclosure. It details the exact categories of comparison (added, removed, retyped, rewired, re-parameterised operators, plus DAT line diff) and notes that moved nodes are counted separately so they cannot hide a real change. A small gap is that it does not explicitly state the operation is read-only, though 'compare' strongly implies it.

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 no filler. The main purpose is front-loaded, the next sentence adds useful comparison detail, and the final sentence clarifies an important behavioral nuance about move handling. 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?

The output schema exists, so return structure is covered. The description does a good job conveying comparison semantics, but the absence of parameter guidance is significant given zero schema descriptions and no annotations. The optional booleans in particular remain underspecified for an agent attempting a correct invocation.

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 description does not explain individual parameters. file, before, after, show_moves, and include_text are left to their names and defaults. The move-counting behavior hints at show_moves, and the DAT line diff hints at include_text, but this is indirect and does not compensate for a 5-parameter tool with zero schema documentation.

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 states a specific verb and resource: 'Compare two saved variants of the same project.' It also differentiates itself from the sibling td_project_diff by specifying that this tool targets two saved states rather than two files, so an agent can tell them apart without opening schemas.

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?

The description explicitly names td_project_diff as the analogous file-based comparison and clarifies that td_variant_diff is aimed at two saved states instead. This gives clear context for choosing between the two tools and implies the when-not condition (use td_project_diff for files).

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