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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint, so safety is covered. The description adds two useful facts: the list is scoped to the authenticated user and only 'available' rooms appear — implying unavailable saved favorites are excluded. It says nothing about ordering, paging, or result shape.

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?

A single front-loaded sentence with no filler. Every word carries meaning, and the scoping terms (authenticated user, saved, available) come before any trailing detail.

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?

With an output schema present, return values need not be described, and zero parameters removes schema risk. The remaining question — what 'available' filters out and how the list is ordered — is a minor gap for a simple zero-arg list tool.

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 takes zero parameters, so there is nothing for the description to explain; baseline 4 applies. No syntax or filter options are implied that the schema would need to document.

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 (List) and resource (the authenticated user's saved available rooms), which is unambiguous. It does not explicitly contrast with siblings like add_favorite or remove_favorite, but the verb makes the read-vs-mutate distinction obvious.

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?

No statement of when to use this over alternatives, no preconditions, no mention of paging or filtering behavior. The agent must infer usage from the name alone.

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