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

Annotations already declare readOnly, idempotent, non-destructive and open-world, and the description adds real value on top: values are per account and must never be aggregated, the read goes directly to the broker, and no account numbers, broker tokens, or runtime secret ids are returned. The stale-read caveat is a behavioral trait the annotations cannot express.

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 read-only summary and return values, then routing rules, then constraints. Most sentences carry distinct information, though the sequencing caveat ('not as a preflight') and the standalone-case restatement add dense but somewhat repetitive qualification that could be tightened.

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 no output schema, the description must describe return values itself, and it names the three fields returned plus the security exclusions and the no-aggregation rule. Combined with the sequencing guidance relative to show_bot_activity, an agent has everything needed to call it correctly and interpret results.

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%, so the description must compensate. It does well for brokerCredentialId, explaining that it must be an exact active saved connection and reused across quote and place_trade, but brokerProvider is never mentioned, leaving half the parameters undocumented. Partial compensation justifies a middle score.

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 ('fetches current cash, buying power, and account value') plus the source ('signed-in user's saved broker connection'), and explicitly separates itself from show_bot_activity by describing that sibling's own behavior. An agent can distinguish it from get_broker_positions and show_account_overview without opening any 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?

Gives explicit when-to-use and when-not-to-use rules: use show_bot_activity first for named-bot performance, then use this tool only for a failed or stale read and not as a preflight, while standalone account questions still use this tool normally. The trade-sizing path (resolve one exact active connection, reuse its brokerCredentialId for the quote and place_trade) is spelled out step by step.

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