Current Session Energy

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

No annotations are provided, so the description carries the full behavioral burden. It never states that this is a side-effect-free read, nor does it disclose the reliability of the estimate, latency, or behavior when no session data exists; 'estimated' hints at approximation but that is all.

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 sentence that front-loads the two returned quantities and the scope. Zero filler and no redundancy with the schema or 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?

With an output schema present, return values need not be described, and a zero-parameter tool is simple. However, the near-total absence of usage and behavioral guidance against zero annotations leaves the agent to infer whether and when this should be called over its sibling.

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 are no parameter semantics to explain. Per the baseline for parameter-less tools, a 4 is appropriate; the description adds nothing here, but nothing is missing either.

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 names the resource ('calling Claude Code session') and the quantified outputs ('energy (kWh) and CO2eq'), so an agent knows what is measured. It implies a read of the current session, distinguishing it from the project-wide sibling, but never names collate_project_sessions_energy explicitly, so sibling differentiation is left to inference.

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?

There is no when-to-use or when-not-to-use guidance, and no reference to the alternative tool for project-level aggregation. The scope word 'calling session' implicitly limits it, but the agent receives no explicit routing instruction.

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