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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds genuinely useful context beyond them: the call fans out over every connected exchange including a sandbox, and all amounts are normalized to USD with USDC/USDT treated as equivalent. It stops short of noting auth requirements or what happens when an exchange account is disconnected or a venue errors, which is the remaining gap for an openWorld aggregation call.

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 returned fields, then triggers, exclusions, and unit semantics in short declarative sentences. The trailing 'Next: get_my_positions' partially duplicates the earlier 'Not for positions' line, which is the only mild redundancy.

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 still supplies the venue coverage and USD normalization an agent needs to interpret them. For a no-input read tool this leaves nothing material unstated.

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?

With zero parameters the baseline is 4, and the description confirms 'No inputs' so an agent won't hunt for a required argument. Nothing further is needed on the parameter side.

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 first sentence names the exact resource (equity, free margin, used margin, open PnL) and its scope (every connected exchange account plus the total), listing the venues by name. It is immediately distinguishable from get_my_positions, which is named as the wrong tool for 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?

It gives positive triggers (report balances, compare free margin across exchanges), an explicit when-not ('Not needed before opening: size_position reads equity itself'), and an alternative for a different need ('Not for positions (use get_my_positions)'). An agent can route on this without opening any schema.

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