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

No annotations are provided, so the description carries the full behavioral burden. It does disclose the return shape (resolved frontmatter with topology, render config, pieces, setup FEN), which is real value, but it says nothing about read-only nature beyond the verb 'Get', error behavior for unknown families/variants, or whether defaults are applied when variant is omitted (that detail lives only in the schema).

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?

Two tight sentences with the resource and returned contents front-loaded and no wasted filler. It could be marginally better by combining the return-field list rather than restating 'definition' twice, but it is efficient.

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 read tool with no output schema, the description compensates by naming the concrete contents returned (topology, render config, pieces, setup FEN, resolved frontmatter). With parameters fully documented in the schema, the only remaining gap is that no annotations exist to confirm the read-only profile.

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 100%: family is documented with a full enumeration and variant notes its default behavior. The description adds only the generic phrase 'for a game variant' and no syntax, slug, or format detail beyond the schema, so the baseline of 3 is appropriate.

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: retrieve the full engine definition for a game variant, and enumerates what it contains (topology, render config, pieces, setup FEN, frontmatter). It is clear what the tool does, though it never distinguishes itself from lookalike siblings such as rules_get_variant or rules_get_game.

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, no prerequisites, and no named alternative. The agent must infer that this is the engine-definition counterpart to rules_* tools from the description alone, which is exactly the kind of routing gap a usage section should close.

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