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

Annotations already declare readOnly/openWorld/non-destructive, so the safety profile is covered. The description adds genuinely non-obvious context: the tool works without a key, an API key unlocks extra ROI metrics, and it returns aggregates rather than signals. It does not disclose pagination or latency, but for an aggregate read tool in a public API this is solid.

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 core purpose, and every clause carries information (scope, metrics, key behavior, sibling routing, disclaimer). The opening sentence is long and dense with many sub-clauses, which slightly hurts scannability but wastes nothing.

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?

No output schema exists, and the description compensates by enumerating the returned metrics and clarifying that individual signals are not returned. Combined with the schema's default/range for days, an agent has everything needed to call and interpret the result.

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 the baseline is 3, but the description adds meaning beyond the schema by explaining what the apiKey parameter actually unlocks (average ROI per signal and cumulative ROI) rather than just restating that it is optional.

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 precise verb+resource (aggregate performance of resolved signals) and enumerates the metrics returned (hit rate, verified count, avg leverage, direction breakdown, ROI). It also explicitly distinguishes itself from siblings by noting it returns no individual signals.

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 an explicit use case ('judge recent reliability before acting') and routes the agent to alternatives for the excluded behavior: 'use get_signals or get_signal_history for those'. When-to-use and when-not-to-use are both covered.

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