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

With no annotations, the description carries the full burden: it discloses that the tool is a read-only query, enumerates the confirmation targets returned, and specifies units (BTC/kvB) plus an extra returned metric (mempool minimum). It does not mention data freshness, caching, or rate limits, so it stops short of fully transparent behavior.

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?

Extremely compact and front-loaded: capability sentence first, then bracketed usage and anti-usage markers. Every clause carries information — targets, units, return extras, trigger intent, and the excluded sibling — with no filler.

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, so the description correctly does the work of explaining return values (fee rates per confirmation target plus mempool minimum, in BTC/kvB). Combined with the routing guidance, an agent has everything needed to call and interpret this zero-parameter tool.

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 tool takes zero parameters (empty schema, 100% coverage trivially), so there is nothing for the description to disambiguate. Baseline 4 applies; the description's mention of confirmation targets is a return-value explanation, not a parameter contract.

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 (query) and resource (Bitcoin recommended fee estimates), plus the exact confirmation targets (1/2/3/6/12/24 blocks) and output units (BTC/kvB). It also names a distinguishing return value (mempool minimum fee rate), which separates it from sibling tools.

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?

Explicit 【何时用】 trigger gives a natural-language user intent ("how much fee should I pay / what gets fast confirmation"), and 【不要用】 names the sibling btc_mempool_summary with the condition that selects it (asking about congestion level). This is textbook when/when-not/alternative routing.

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