fetch_performance

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

No annotations are provided, so the description carries full burden. It mentions that the tool 'retrieves' metrics and may return 'None if failed', which implies read-only behavior and error handling. However, it lacks details about authentication needs, rate limits, what specific metrics are included, or whether this is real-time vs historical data - significant gaps for a financial tool with no annotation coverage.

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 efficiently structured with a clear purpose statement followed by parameter and return documentation. The two-sentence format is appropriately concise for a zero-parameter tool, though the 'Parameters' section could be omitted since there are no user-facing parameters.

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 trading performance tool with no annotations and no output schema, the description is insufficient. It doesn't explain what 'performance metrics' include (returns, Sharpe ratio, drawdown, etc.), whether this is for current/live trading or historical periods, or how the stringified JSON is structured. Given the complexity of financial metrics and lack of structured output documentation, this leaves too much ambiguity.

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 0 parameters, and schema description coverage is 100% (though empty). The description correctly notes there are no user-facing parameters beyond the MCP context object, which is appropriate. No additional parameter information is needed or possible.

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 states the tool 'retrieves trading performance metrics', which is a clear verb+resource combination. However, it doesn't distinguish this from sibling tools like fetch_balance, fetch_profit, or fetch_backtest_history, leaving the specific scope of 'performance metrics' ambiguous compared to these alternatives.

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?

No guidance is provided about when to use this tool versus alternatives. With multiple fetch_* siblings (fetch_balance, fetch_profit, fetch_backtest_history, etc.), the description offers no context about what distinguishes performance metrics from other retrievable data or when this specific tool is appropriate.

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