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

Goes well beyond the annotations: it discloses the return payload shape (up to first 100 trades with entry/exit time and price, direction, P&L percent, exit type, trades_total), a retention rule (runs older than the newest 200 are discarded), cross-account behavior (another account's id reads as not found), and the auth requirement. The annotations only cover the safety profile, so this adds substantial independent value.

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-loaded with the core return content, then usage, then id provenance/edge cases, then auth. Every sentence carries information, though the single dense paragraph could be split for readability.

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?

Despite an output schema existing, the description still summarizes the returned trade fields and explicitly notes the equity curve is not included. Combined with retention, error, and auth details, an agent has everything needed to call this correctly.

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 100% and the schema already documents the parameter, so baseline is 3. The description earns above baseline by specifying provenance (the id comes from run_backtest or get_my_backtests), a retention consequence for stale ids, and not-found semantics for foreign ids.

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+resource ('Returns one of your stored backtest runs') and immediately distinguishes it from the sibling get_my_backtests by noting it includes the trades that tool leaves out. An agent can tell exactly what this returns and how it differs from the other backtest tools without opening a schema.

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 names the use case ('Use it to see why a run won or lost after run_backtest or get_my_backtests') and references the alternative it complements. It also clarifies a boundary ('the equity curve is not returned'), which prevents a plausible misuse.

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