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

Annotations already establish read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower, yet the description adds genuine value beyond them: data provenance per lane and explicit failure semantics ('missing mapping or broker failure is an explicit equity error, not a virtual stock balance or zero valuation'). That error-behavior disclosure is exactly the kind of context annotations cannot express.

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?

Three compact sentences, front-loading the source-per-lane model before the error caveat. Dense with jargon but each clause carries information; the 'not a virtual stock balance or zero valuation' clause usefully disambiguates failure behavior rather than padding.

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 one optional parameter, the description should carry more of the return-shape burden than it does. It covers provenance, auth, and failure semantics well, but says nothing about what fields the portfolio response contains or how the competition scoping changes the result.

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?

There is a single optional parameter with 100% schema description coverage, so the schema already explains that 'competition' scopes the call to a sub-book. The description adds no syntax, format, or default information for it, so the baseline of 3 is appropriate.

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 conveys that this returns the caller's own portfolio across distinct lanes (equities via Alpaca paper, perps and predictions/UD5M via virtual orderbooks), which gives a partial sense of the resource. However, the verb is implicit and it never distinguishes itself from the very similar siblings get_portfolio and get_my_positions, so an agent cannot confidently route between them from the text alone.

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 only usage-relevant statement is 'Agent key required,' a prerequisite rather than a when-to-use rule. There is no guidance on when this should be chosen over get_portfolio, get_my_positions, or get_my_orders, and no conditions for the optional competition scoping.

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