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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds non-obvious behavior beyond that: stopped and pending instances still consume a slot toward the max-10 limit until deleted, which is genuinely useful operational context an agent cannot infer from the schema or annotations.

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?

Two tight sentences, front-loaded with the action and resource, followed by the one non-obvious constraint. No filler or repetition.

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 annotations cover the safety profile. For a parameterless read-only listing tool the description supplies everything an agent needs to call it correctly, including the quota caveat.

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?

Zero parameters, so with schema coverage at 100% and annotations present there is nothing for the description to disambiguate. The parenthetical field list describes the shape of results, which is mildly useful but not a parameter concern.

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?

Specific verb+resource ('List trading instances') plus the key returned fields (id, name, status, is_live, broker), which makes the resource unambiguous against siblings like list_my_algos, list_backtest_runs, and list_pending_trades. It stops short of naming a sibling to contrast against, so it lands at 4 rather than 5.

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?

Usage is implied by the tool's nature (enumerate instances, e.g. to find an id for start_instance/stop_instance/delete_instance), but the description gives no explicit when-to-use or when-to-prefer-an-alternative guidance. The max-10 slot note hints at the delete decision context, which is a partial help.

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