btc_fees

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

With no annotations, the description carries the full burden and does well: it discloses the cost ($0.002 USDC per call) and p99 latency (2000ms), which are behavioral facts not available anywhere else. It stops short of stating authentication requirements or rate limits, and read-only status is only implied rather than declared.

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?

Purpose is front-loaded and the cost/latency facts are appended usefully. The opening 'Bitcoin Fee Estimate — Bitcoin fees right now' is slightly redundant, and the return-value list is a dense run-on sentence, but overall it is appropriately sized for a no-parameter data tool.

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 compensates by enumerating the return fields explicitly, and it adds cost and latency metadata. For a zero-parameter, annotation-free data fetch, nothing an agent needs to call it correctly is missing.

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, so there is nothing for the description to clarify about inputs. Baseline 4 applies; no parameter-level gaps exist.

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 names a specific verb+resource (Bitcoin fee estimate) and enumerates exactly what it returns: recommended sat/vB for next block, 30 min, 1 hour, economy, USD payment cost, mempool size, tip height, difficulty adjustment, and BTC price in USD/EUR. The explicit 'Bitcoin' scoping naturally separates it from the sibling gas_price (EVM). An agent can tell what this tool delivers without opening any schema.

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 when-to-use trigger: 'Call before sending a Bitcoin transaction.' That is actionable context. However, it names no when-not conditions and no alternatives (e.g., gas_price for EVM chains, crypto_prices for spot prices), so routing is implied rather than explicit.

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