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

Annotations are all false, providing minimal behavioral info. The description compensates richly: the session waits for Begin, the result explains why it was picked and which stages it has, it may appear in chat or via a web link, the session moves through named stages, and the breathing pattern is hold-free. No contradiction with annotations.

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 longer than average, but every sentence carries useful information, especially given the lack of an output schema. It is front-loaded with purpose and trigger, then covers behavior and result. It could be tightened slightly but is not wasteful.

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 3-parameter tool with no output schema, the description is thorough: it explains when to invoke, what happens during the session, what the result contains, client-specific rendering, and the breathing style. There are no obvious missing pieces an agent would need to call 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?

Schema coverage is 100% with detailed enum descriptions, so baseline is 3. The description adds a meaningful nuance for minutes: 'Longer sessions move through more stages, not just more time,' which goes beyond the schema. It also restates the three inputs coherently without adding conflicting syntax.

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 is specific: it states the verb 'Matches', the resource 'VirWave session', and exactly how the matching works (feeling clarity, desired alternative, length). It also distinguishes this from siblings by targeting the app's entry flow, which is clearly separate from simple breathing (breathe) or pattern lookup (list_patterns).

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?

Provides an explicit trigger: 'Invoke it when someone says how they are feeling, or what they would like to feel instead, and wants a breathing session that fits.' This is clear and actionable context, though it does not explicitly name sibling tools or state when not to use them.

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