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

Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=true, so 'safe to repeat' and 'places no trades' largely restate structured data. The genuinely new behavioral information is the asynchronous workflow — the operation is not complete on return, and the caller must poll get_account_status until `ready`.

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?

A single dense sentence plus a short example. The key behavioral fact (poll until ready) is front-loaded, and nothing is wasted.

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 values need no explanation, and the description supplies the one thing the schema cannot express: that the call is asynchronous and must be followed by status polling. Nothing an agent needs to invoke and complete this workflow 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 explains that account ids are UUIDs from list_accounts rather than MT5 login numbers. The description adds only a minimal example payload, 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 gives a concrete verb and resource: it starts each account's MT5 terminal in the cloud and logs it in. It is immediately distinguishable from siblings such as take_account_offline and the read-only get_account_status.

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 tells the agent what to do after calling (poll get_account_status until `ready`) and clarifies the effect boundary (places no trades, safe to repeat). It does not explicitly state when to prefer this over alternatives, but the async completion path is clearly prescribed.

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