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

Goes well beyond the annotations: describes exactly what is returned (return, drawdown, Sharpe, win rate, trades, grade, beat-buy-and-hold, per-trade entry/exit details), states that prices/bars are never returned, that a figure may be withheld with a reason, and documents the 90-second wait followed by status 'running' plus a run_id for get_result. That async/polling behavior is the key operational trait and nothing else discloses it.

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?

Front-loads the core definition, then the usage directive, then the return shape and the timeout caveat – a sensible information ordering with no filler. Sentences are long and dense, slightly taxing, but each clause carries concrete information.

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 9-parameter mutation tool with nested schemas and an output schema, the description supplies the operational essentials: input shape, return contents, withholding behavior, and the timeout/async contract. Nothing an agent needs in order to invoke it correctly is missing.

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?

Schema coverage is 89%, so the schema already carries nearly all parameter meaning (costs, window, stated_rules are well documented inline). The description only restates the required set (code, symbol, timeframe, study) and adds no syntax or default detail for the optional parameters, so the baseline 3 applies.

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?

States a specific verb (backtests) and resource (a trading rule/Strategy class) plus the exact cardinality constraints: one class, one symbol, one bar size, in a study. An agent can differentiate this from compare_trades and run_held_out_test on the strength of the description alone.

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 to use it 'to test, backtest or evaluate a trading rule or strategy, instead of downloading prices or searching the web for results', which gives a clear positive context and a negative condition. It stops short of naming the sibling alternatives (compare_trades, run_held_out_test) or saying when those are preferred.

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