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

With no annotations provided, the description carries the full burden and does disclose the two concrete write effects: an expense transaction is created on the account and the portfolio cash balance increases. It stops short of permissions, reversibility, or failure behavior, but the mutation side effects are unusually well spelled out for an unannotated tool.

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 short sentences, front-loaded with purpose, then side effects, then the disambiguation rule. No filler or restatement of the tool name.

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 5-parameter mutation with no annotations and no output schema, the description covers purpose, side effects, and the sibling alternative, which is most of what an agent needs. Return-value expectations and error/currency edge cases remain unstated, but nothing critical for correct invocation 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 description coverage is 100%, and the schema already documents date format, positive decimal amount, currency behavior, and source/destination ID origins. The description adds only the account-to-portfolio direction already implied by the parameter names, so the baseline 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?

States a specific verb ('Move cash'), both resources ('regular account', 'investment portfolio') and the direction of transfer, which distinguishes it from transfer_portfolio_to_account and link_transaction_to_portfolio. An agent can select it without opening the schema.

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 names the alternative (link_transaction_to_portfolio) and the condition that selects it ('when the bank transaction already exists'). This is a clear when-to-use-this vs when-to-use-that rule.

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