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

With no annotations, the description carries the burden and does well: it discloses that results are SIMULATED, that long runs are paged via offset, and spells out the auth/payment model (x402 per-call charge vs. API key). It stops short of stating ordering, max page size, or what an empty/expired backtest_id returns.

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 what the tool returns, then disambiguation, then the simulated-vs-real warning, then paging, then access. Every sentence carries distinct information; the payment block is bracketed so it doesn't obscure the core purpose.

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 paged read tool with no output schema and no annotations, the description covers return content, data provenance, pagination, and cost. Minor gaps remain around ordering and page-size behavior, but nothing that would cause a mis-call.

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%, so baseline is 3, but the description adds real signal: it tells the agent that offset exists because long runs are paged and should be passed to 'read on', which the schema's generic pagination text does not convey.

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 ('the individual trades a backtest made') and enumerates the payload (entry/exit prices and times, P&L, close reason). It explicitly distinguishes itself from get_backtest (summary metrics) and list_trades (real trades), so an agent can route 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?

Gives the exact trigger ('when the user asks what a backtest actually traded'), names the alternative for summary metrics, names the alternative for real trades, and adds the paging condition. Both when-to-use and when-to-use-something-else are covered.

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