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

Annotations already declare readOnlyHint, idempotentHint and closed-world, so safety is covered; the description adds genuinely new behavior: variables surface as {NAME} placeholders and their values are never returned. That is exactly the kind of disclosure the agent cannot get from structured fields. It omits what happens when no guide of the requested kind exists.

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 short sentences, front-loaded with what is returned, then how to select, then the caution. No filler and nothing repeated verbatim from annotations.

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-shape detail is unnecessary, and the description still covers the non-obvious return quirk (masked variables). Combined with the selector semantics and the read-before-edit rule, an agent has enough to call this 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?

Schema coverage is 100% and each parameter already carries a description, so the baseline is 3. The description usefully adds precedence between guide_id and kind and names the sibling tools that produce a guide_id, but it largely restates what the schema already says about kind and its default.

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 plus the exact payload returned ("its text, name and version"), which is concrete. It does not, however, distinguish itself from the similarly named sibling get_guide_instructions, leaving the agent to infer which one returns the saved document.

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 two explicit selection modes (pass guide_id for a specific guide, or kind for the newest of that kind) and a concrete precondition: "Read it before changing a guide you did not write." No exclusion against get_guide_instructions is offered, so it stops short of full alternative routing.

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