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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered elsewhere. The description's added value is disclosing what the result set contains (the metric inventory), which substitutes for a missing output schema. It says nothing about aggregation behavior, whether the window boundaries include the current partial month, or what happens when no trades exist in a period.

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?

A single dense sentence, front-loaded with the resource name followed by the measure list. Every clause names a distinct output dimension, so nothing is filler. The enumeration is long but earns its place given there is no output schema.

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 and only two trivially documented parameters, the description's primary job is to describe the return payload, and it does so thoroughly across monthly, per-underlying, and closed-trade aggregates. The remaining gap is behavioral/edge-case context rather than coverage of what the tool returns.

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 description coverage is 100% — both `months` (range 1-120, default 12) and the optional `symbol` are documented in the schema itself. The description adds no meaning beyond that, never mentioning either parameter. Baseline 3 applies since the schema carries the burden.

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 names the resource precisely ("the user's option premium history") and enumerates the measures it covers: credits/debits/net by month and underlying, retention, contracts traded, average days to expiry at open, and the closed-trade record. That is specific enough to distinguish it from the position or order tools. It does not, however, explicitly separate it from my_closed_option_trades, which overlaps with the closed-trade portion.

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?

There is no explicit statement of when to call this versus alternatives, despite a clear sibling overlap with my_closed_option_trades and my_option_payoff. Usage is only inferable from the metric list. No prerequisites, no exclusions.

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