get_session_stats

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

No annotations are provided, so the description carries the full burden. It clearly indicates idempotent reading via 'Get' and lists returned fields. It does not disclose potential side effects (unlikely) or authorization requirements. The active session fallback is described in the parameter schema but not in the description itself.

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 extremely concise: a single sentence with a bulleted list of return values. No extraneous text, immediate purpose statement, and structured enumeration of outputs.

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 simple read tool with one optional parameter and an output schema, the description covers the primary purpose and all return fields. It does not detail the optional parameter's default behavior (covered by schema) or compare to siblings, but completeness is adequate given low complexity.

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 input schema provides 100% coverage for the single parameter session_id, describing its dual type, default, and behavior ('Uses active session if not provided'). The tool description only restates 'chat session' without adding semantic nuance. Baseline 3 is appropriate given schema completeness.

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 starts with a clear verb ('Get') and resource ('current metrics for a chat session'), and the bulleted list of return values specifies exactly what is retrieved. This distinguishes it from siblings like get_session_summary (likely a text summary) and get_plan_usage (different resource).

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 states the tool's purpose but does not explicitly say when to use it over alternatives like get_session_summary. There is no when-not or conditional guidance, only a general statement of what it does.

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