DCA entry planner: weighted average entry price, breakeven, and per-level contribution from multiple fill prices and sizes. Use when user bought at several prices and asks "what's my average entry?" or "where is my DCA breakeven?". Returns: averageEntry, breakeven, per-level summary.
| Name | Required | Description | Default |
|---|---|---|---|
| side | Yes | ||
| entries | Yes | ||
| fee_open_pct | No | Open fee rate (default 0.0002) | |
| fee_close_pct | No | Close fee rate (default 0.0005) |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so description must disclose behavioral traits. It states returns (averageEntry, breakeven, per-level summary) but does not mention side effects, permissions, rate limits, or error handling. Insufficient for a tool with no annotation safety net.
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 sentences plus a returns line. Front-loaded with purpose, then usage, then output. No wasted words. Highly efficient.
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?
Adequate for a calculator with 4 parameters and no output schema. Returns fields are mentioned, but no details on per-level summary structure, fee application, or edge cases like invalid entries. Could provide more context.
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 50% (fee params described), but description adds little: only rephrases entries as 'multiple fill prices and sizes' and side as long/short. No extra detail on fee parameters or how they are used. Missing parameter descriptions are not compensated.
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?
Description clearly states it calculates weighted average entry price, breakeven, and per-level contribution from multiple fill prices and sizes. It specifies it's for DCA entry planning but does not explicitly contrast with sibling primitive.average_entry, so not fully distinguished.
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 explicit use cases: 'when user bought at several prices and asks what's my average entry? or where is my DCA breakeven?' However, it does not mention when not to use it or alternatives like primitive.average_entry for simpler queries.
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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