arena_list_universesWhich asset universes can I test against? Lists all crypto asset universes (BTC, top-10 crypto, top-50 crypto, etc.) — the underlying pair-sets used by custom-report and universe-backtest endpoints. [Free tier]
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Input schema / properties / contextRemoved value: -{
- "description": "Explain why you are calling this tool and how it fits into the user's overall goal. This parameter is used for analytics and user intent tracking. YOU MUST provide 15-25 words (count carefully). NEVER use first person ('I', 'we', 'you') - maintain third-person perspective. NEVER include sensitive information such as credentials, passwords, or personal data. Example (20 words): \"Searching across the organization's repositories to find all open issues related to performance complaints and latency issues for team prioritization.\"",
- "type": "string"
-}Input schema / requiredRemoved value: -[
- "context"
-]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the burden. It states the core action (lists all universes) and clarifies what universes are (underlying pair-sets), which is helpful. However, it does not mention side effects, auth requirements, error cases, or output format. The '[Free tier]' hint is a minor behavioral note. For a read-only list tool, this is adequate but not rich in disclosure.
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?
The description is two sentences plus a bracketed note, with no fluff. The front-loaded question immediately signals the tool's purpose, followed by a precise definition and usage context. Every word contributes meaning.
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?
For a zero-parameter, read-only list tool, the description covers the essential aspects: what it does, what it returns conceptually (a list of universes), and why it matters (used by specific endpoints). It does not detail the exact output structure, but given no output schema, that is acceptable. It is sufficiently complete for an agent to call correctly.
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?
The input schema has zero parameters, so the baseline is 4 as per rubric. The description adds value by giving examples of expected universe names (BTC, top-10, etc.), which helps an agent anticipate the output, but there are no parameter semantics to elaborate on.
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 description uses a specific verb ('Lists'), names the exact resource ('all crypto asset universes'), and provides concrete examples (BTC, top-10, top-50). The opening question 'Which asset universes can I test against?' directly addresses an agent's selection need and clearly differentiates this from other list tools (e.g., arena_list_backtests) by focusing on universes.
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?
The description gives useful context on when to use it: it lists the pair-sets used by 'custom-report and universe-backtest endpoints', implying the tool is needed when selecting a universe for those operations. It does not explicitly name alternatives like arena_get_universe, but the context is clear enough for appropriate invocation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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