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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered; the description still adds a real trait beyond them by noting no LLM call is made (cost/latency implication). It does not describe error behavior for an unknown slug, so it stops short of a 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?

Two tight sentences with the resource and key first and the non-obvious LLM-cost remark second; no filler.

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?

An output schema exists so return values needn't be explained, and the description still enumerates the returned facets. For a single-parameter, read-only, closed-world lookup it is nearly complete, missing only slug format or missing-arena behavior.

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 carry the parameter burden; it does only minimally by saying lookup is 'by slug', establishing that the identifier is a slug. It gives no format, examples, or slug-source guidance, leaving the lone required parameter thin.

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 (Read) and resource (one arena) and enumerates exactly what is retrieved: ruleset, scenario, capabilities, limits, status, keyed by slug. The 'one ... by slug' phrasing clearly separates it from list_garden_arenas.

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 context is implied rather than stated: 'This performs no LLM call' hints that this is the cheap inspection step before the *_run tools, but no alternative or when-not condition is named explicitly. An agent must infer that list_garden_arenas is for enumeration and this is for a single lookup.

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