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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context beyond the annotations by warning that the guide is long and should be read once, which helps an agent avoid repeated expensive fetches.

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 description is two sentences, front-loads the tool's identity, then packs the guide's contents and the key usage note ('read it once') without redundancy. Every clause 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?

For a zero-parameter, read-only reference document with no output schema, the description explains what the guide covers and how to use it. It stops short of describing the return format (e.g., text/markdown) or whether the content is static, but nothing critical is missing for 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?

The tool has zero parameters, so there are no parameter semantics to explain; baseline 4 applies. The description correctly focuses on the returned content rather than inventing nonexistent inputs.

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 exactly what the tool returns: the guide for writing an invented game, with a specific inventory of contents (template, logic/view APIs, luck/skill rules, examples, and check/save steps). It is clearly distinguishable from sibling tools like invent_game or check_invented_game because it is the reference document rather than the authoring action.

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?

Context is clear: this is for writing an invented game yourself, and the closing 'Long: read it once' gives explicit usage guidance about not refetching. It does not name alternatives or explicitly say when not to call it, so it falls short of a full 5.

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