get_ai_usage

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

With no annotations, description carries full burden: discloses in-memory tracker, never throws, returns zero when no key or no calls. Provides sufficient behavioral context.

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?

Two sentences, no waste. First sentence defines purpose, second lists outputs and usage recommendation. Front-loaded and efficient.

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?

Given zero parameters and no output schema, description adequately covers return shape and session context. Slightly lacking details on session lifecycle, but minor.

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?

No parameters exist (baseline 4). Description adds meaning about return structure, fulfilling the need.

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?

Description clearly states it returns AI token usage and estimated cost for the MCP session, lists specific return fields, and mentions it monitors spend from specific sibling tools (analyze_design, design_doc, compose).

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?

Explicitly says 'Use to monitor spend from analyze_design, design_doc, or compose', providing clear context for when to use. No exclusions needed due to unique functionality.

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