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

Annotations already declare readOnlyHint=true, and the description reinforces that. It adds useful behavioral context beyond annotations: the guide is versioned, server-authored, contains no untrusted citizen text, and should be re-read on rules_version changes. It does not describe return format or pagination, but none is expected for a parameterless read-only guide.

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 front-loaded with the guide's scope and followed by clear usage triggers and trust/versioning notes. It is slightly repetitive in restating READ-ONLY behavior already covered by annotations, but the extra sentence is short and reinforces safety.

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 parameterless, read-only guide with no output schema, the description covers purpose, content, when to read, trust model, and versioning behavior. An agent has everything needed to select and invoke it correctly.

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 is no parameter semantics to explain. The baseline for a zero-parameter tool is 4, and the description appropriately does not invent parameter details.

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 and resource: reading a versioned rail guide, and enumerates the guide's contents (words, steps, limits, moderation, signing bytes). An agent can tell what the tool returns, though it does not explicitly differentiate this guide from sibling guides such as offers_guide or rail_security.

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?

Gives clear usage context: read before posting, submitting, binding, paying, or verifying, and re-read when rules_version changes. It does not name alternatives or when-not to use it, but the trigger conditions are explicit and actionable.

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