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

Annotations already declare readOnly, idempotent, non-destructive, and non-open-world, so the safety profile is covered. The description only adds that the stats are 'aggregate' and scope-able, with no detail on what aggregation window or entity the figures cover, so it adds modest value.

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 tight sentence with the trigger front-loaded and the scope qualifier trailing. No wasted clauses, though the framing as a user-question trigger is slightly indirect.

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 an output schema present, return values need not be explained, and annotations carry the safety profile. The description is adequate for a 2-parameter, zero-required read tool, though it could say more about what 'aggregate' spans.

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% with both parameters documented and enumerated. The description's note that results are 'optionally scoped by source and period' restates optionality already visible in the schema, adding little beyond the baseline.

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 (aggregate market stats) and enumerates the concrete contents (positions, PNL, win rate). It does not differentiate from the close sibling get_signal_stats, so an agent must still infer which 'stats' tool applies.

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 a clear triggering condition ('when the user asks for aggregate market stats') with concrete examples of the metrics. However, it names no alternative or exclusion, so the agent gets no routing guidance against siblings like get_signal_stats or get_positions.

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