list_positions

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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds valuable behavioral context beyond annotations: it explains that flat positions are retained for lifetime P/L, and details the exact shape of the response with field meanings (e.g., 'units' positive/negative). This exceeds baseline but stops short of disclosing pagination or other potential edge cases, so 4 is appropriate.

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?

The description is front-loaded with the core purpose, then the alternative, then a structured breakdown of the return format. Every sentence contributes unique information, and the use of code formatting for the response keys improves skimmability. No extraneous content.

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 list tool with a nested position structure, the description fully specifies return fields, side semantics, and decimal string conventions. Although an output schema exists, the description's elaboration on field meanings adds practical completeness that makes the tool immediately usable.

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?

The only parameter 'limit' is fully described in the schema (100% schema description coverage) with type, default, and minimum. The description does not add further parameter nuance, but since the schema covers it completely, the baseline of 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?

The description uses a specific verb ('List') and clearly identifies the resource ('every position the account has ever held, one per instrument'). It explicitly distinguishes itself from list_open_positions by stating it includes flat positions, which sets it apart from its sibling.

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?

The description explicitly states when to use this tool ('List every position... includes flat positions') and when to use an alternative ('use list_open_positions for current exposure only'). This gives direct guidance on tool selection.

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