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 fully covered without the description. The description adds only that the payload is markdown and that guides are prep material — useful but thin, with no statement on size, paging, or caching.

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 short sentences with zero filler: what it does and returns first, then how to pick a topic and when to reach for it. Nothing restates the title.

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-value explanation is unnecessary, and the single enum parameter is fully specified in the schema. Combined with the discovery pointer to list_guides, an agent has everything needed to call this correctly on the first try.

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 the sole parameter is a 14-value enum documented inline, so the schema carries the full burden. The description's only addition is pointing at list_guides as the way to discover valid topics; it adds no per-topic meaning beyond the enum.

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?

Specific verb (fetch) plus specific resource (a Tessryx guide by topic) and even the return format (markdown). It is clearly distinguishable from every sibling, all of which operate on platform resources rather than documentation.

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?

Explicitly routes discovery to list_guides and states the trigger condition for calling it: consult the relevant guide before authoring to avoid trial-and-error. Both the alternative and the when-to-use condition are stated outright.

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