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

Annotations only declare the generic mutation profile (readOnly=false, destructive=false, not idempotent); the description goes well beyond them by disclosing the mandatory plan/confirm approval gate, that a plan expires after 5 minutes, and that the call creates both a portfolio and an account without any trading. This is exactly the operational context an agent needs before mutating state.

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 tight sentences, front-loading the purpose before the operational flow. The dense plan/confirm sentence is warranted because every clause is an actionable instruction; there is no filler.

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 an output schema present, the description needn't document return values, and it correctly references plan.human_message rather than re-describing it. The remaining gap is that four of six input parameters carry no meaning anywhere, which is the only thing an agent could mis-handle.

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 0% across six parameters, so the description must compensate. It usefully explains the semantics of confirm and plan_id within the plan flow, but leaves name, currency, institution, and household_id (all defaulting to empty values) entirely unexplained, so the compensation is partial.

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 ('Create an empty portfolio') and clarifies the side effect ('and the account it sits in') plus scope (in the user's household, e.g. one per bank or broker). The line 'Records structure only; nothing is bought or sold' sharply distinguishes it from trading/mutation actions an agent might assume.

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 prescribes the two-phase flow: call without confirm to get a plan, show plan.human_message to the user, then call again with confirm=true and plan_id only on approval. It also bounds the workflow with the 5-minute expiry, leaving nothing material to inference.

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