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

Annotations declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), but the description adds behavior the annotations cannot express: no buy/sell semantics, candidate-return on ambiguous matches, the two-step plan/confirm approval gate, and the bond-specific meaning of quantity. This is exactly the extra context a mutation tool needs.

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?

Four sentences, each carrying distinct information: purpose, disambiguation, the confirm/plan flow, and the bond edge case. Front-loaded with the core action and free of 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?

An output schema exists so return-value explanation is unnecessary, and the description covers the two non-obvious interaction paths plus one edge case. The remaining gap is the quartet of undocumented optional parameters, which is minor for an add operation but not zero.

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 9 parameters, so the description must compensate. It does explain security (ISIN preferred, ticker/name acceptable), quantity (nominal for bonds), confirm, and plan_id, but leaves as_of, currency, household_id, and cost_basis_per_unit entirely undocumented in both schema and description.

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 ('Record a holding the user already owns') and immediately bounds the scope with 'Never buys or sells', which cleanly separates it from a trade/execute tool. The security+quantity+portfolio framing makes the resource unambiguous against siblings like create_portfolio or get_portfolio_positions.

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?

Gives explicit when-to-use guidance and two conditional flows: the disambiguation path ('if the name matches several securities the tool returns the candidates — ask the user which, then call again with that ISIN') and the Modification Plan flow (call without confirm, show plan.human_message, re-call with confirm=true and plan_id). The agent knows exactly when and how to call it.

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