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

Annotations already flag destructiveHint=true and non-idempotency, and the description adds real operational context on top: reconnects take ~1 minute, credential/server changes are free, but a different account number counts as an add billed every 30 days or 3 USD. That cost/side-effect disclosure is exactly the kind of thing an agent can't get from the schema.

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?

Front-loaded with the purpose, then grouped by scenario (disable, MetaTrader free vs paid). Dense but every clause carries operational meaning; the parenthetical pricing/billing detail is slightly compressed but not wasteful.

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 an 8-parameter destructive mutation with no output schema and full schema coverage, the description covers cost, reconnect timing, and the disable-vs-delete distinction. It doesn't state whether unspecified fields are left untouched or that accountId must reference an existing account, leaving a modest gap.

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 coverage is 100%, so a 3 is the floor; the description earns above that by explaining the interaction between parameters — that email effectively defines a new login and only becomes a paid account switch when combined with password and server. subAccountId semantics are repeated from the schema, limiting the upside.

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+resource ("Update a broker account configuration") and enumerates what is mutable: label, environment, credentials, server, active status, subAccountId. This clearly separates it from create_broker_account/delete_broker_account/get_broker_accounts, though those siblings are never named explicitly.

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?

Implies alternatives through concrete conditions: "Setting isActive to false disables the account for trade execution without deleting it" steers the agent away from delete_broker_account when it only wants to suspend trading. The MetaTrader paragraph explains when an update becomes a paid add versus a free reconnect. No explicit when-not guidance or named sibling routing, so not a 5.

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