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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description still adds substantial non-obvious behavior: bars are deliberately withheld, a forming bar may be present, and defaults fall back to the current chart. It also disambiguates the return semantics (lastClosedCandle as one exact OHLC bar vs. whole-window high/low with highAt/lowAt timestamps).

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 contract (handle, not bars) in the first sentence and packs each subsequent clause with a distinct caveat. The back half is dense semicolon-separated jargon, but nearly every clause carries information an agent needs.

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?

With no output schema, the description carries the full burden of describing the return value and does so: handle, summary, lastClosedCandle, window extreme fields with timestamps, from/to boundaries, and the bars/closedBars relationship. An agent has enough to call it and interpret the result 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 83%, so the baseline is 3; the description goes beyond it by explaining the closed-vs-forming bar implication of `bars` and by clarifying that unspecified market/symbol/timeframe default to the chart. It does not touch `withDerivatives` or the enum choices, leaving a small gap.

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 and resource ('Load price history') and immediately defines the distinctive output contract: a handle plus summary, not the bars. That contract separates it from the compute siblings in a way an agent can act on 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 directs the agent to pass the handle to the compute tools rather than expecting bars back, and gives a concrete sizing rule ('request N+1 for N closed bars and check closedBars'). It stops short of naming the specific sibling (e.g. indicator_compute) or stating when not to use it, but the routing guidance is clear.

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