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

Annotations already cover readOnly/idempotent/non-destructive/openWorld, and the description adds real context on top: a free tier subject to a daily per-caller quota, a deliberately truncated field set, and the requirement that payment credentials go in MCP request headers (X-Payment / X-Payment-Tx / Bearer fg_…) rather than parameters. That auth and rate-limit detail is exactly the kind of thing annotations can't express.

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 lead paragraph is front-loaded and useful, but the following [zh]/[en] block largely restates it — the vendor asset name and the argument list (limit, chain, source) appear twice more, and the free/quota fact is repeated. Roughly half the text is duplication across languages.

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 no output schema, the description correctly spells out the return payload and the payment mechanism, which are the hard parts. However, it leaves all three undocumented parameters opaque and says nothing about what happens at the daily quota limit, so it is adequate rather than complete.

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 description coverage is 0% and all three parameters (limit, chain, source) are bare strings/numbers with null defaults. The description only says they are optional and lists their names, which the schema already conveys; it adds no meaning about valid values for chain/source, how limit is bounded, or how source changes behavior.

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 states a concrete question the tool answers ("what tokens are being promoted right now") and enumerates exactly what the free tier returns: candidate count, chains with candidates, and the top 3 symbols. It also explicitly distinguishes itself from the paid sibling heat_board, which carries full addresses, spend, price, liquidity and FDV.

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?

It gives a clear selection rule: use this tool for the free snapshot, and use heat_board's paid tier when full addresses, promotion spend, price, liquidity or FDV are needed. It doesn't cover when to pick this over non-token-heat siblings, but the free-vs-paid routing is explicit.

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