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

Annotations already establish a safe read of a closed world, so the marginal bar is lower, and the description clears it by disclosing ordering (newest first), that open positions never appear, and that date bounds bind on the open day rather than the close day. The non-obvious explanation that cap and equal weightings trade at identical prices but differ in size and P&L is real behavioral context an agent could not infer from the schema.

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?

Two sentences, front-loaded with the resource and ordering before the weighting variants and the sibling redirect. The stacked parentheticals on weighting are dense and slow a first read, but essentially 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?

For a four-parameter read tool with full schema coverage, annotations, and an output schema, the description covers the remaining ambiguity: what is excluded (open positions), ordering, truncation without paging, and date-bound semantics. Nothing needed to invoke it correctly is missing.

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 a 3 is the baseline, but the description goes beyond it: it explains what the weighting choice actually changes (size and P&L despite identical prices) and clarifies that dates filter on the opening day, which the schema's "earliest date to include" does not say. The limit/no-paging behavior is reinforced with the workaround of narrowing dates.

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?

"Get the paper portfolio's closed trades from resolved books, newest first" names a specific verb, resource, source scope, and ordering. It explicitly separates itself from get_simulation_nav (portfolio value) and implicitly from position-oriented siblings by stating open positions never appear.

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?

It states the use case (individual trades) and names the alternative with its distinct purpose (get_simulation_nav for portfolio value), plus a concrete remedy for truncation: narrow the date bounds. The exclusion of open positions is stated outright rather than left to inference.

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