session_health

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

Annotations already indicate readOnly, idempotent, and non-destructive behavior. The description adds meaningful behavioral context beyond these: it reports live transport status, separates two failure modes, and specifies different return shapes for standalone versus extension-attached modes. This is exactly the kind of contextual detail that helps an agent predict behavior.

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 two sentences with no wasted words. The primary purpose is front-loaded, followed by the key usage condition and then the return-value details. Every clause contributes practical information for tool selection and invocation.

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 zero-parameter diagnostic tool with no output schema and safety annotations already provided, the description is complete. It explains what the tool reports, why it should be called first during failures, and what fields to expect in each mode. An agent has everything needed to invoke and interpret the result.

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, and the schema describes this completely with an empty properties object. Per the baseline for zero-parameter tools, no parameter explanation is required; the description adds no parameter semantics because there is nothing 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?

The description uses a specific verb and resource: 'Report which transport is live and what it can do.' It also clarifies its diagnostic role by saying 'Call this first when another tool fails unexpectedly', which clearly separates it from the sibling action tools like session_navigate or session_click.

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?

The description gives explicit when-to-use guidance: 'Call this first when another tool fails unexpectedly' and explains how it distinguishes root causes. It does not explicitly name alternatives or when-not-to-use scenarios, but the condition and ordering are clear enough for a diagnostic tool with no direct sibling equivalent.

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