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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely non-obvious behavior: the data comes from a periodic snapshot rather than a live query, the country list is a ranked sample of 100 leaderboard nodes rather than full coverage, and billing is $0.002 USDC per successful call with failures not charged. It does not disclose snapshot freshness/update cadence, which is the main remaining behavioral question for a snapshot-based dataset.

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 payload enumeration is front-loaded in the first sentence, followed by sibling routing and pricing. Every sentence carries information, though the opening sentence is very dense and the per-call pricing boilerplate adds length that is only marginally useful before a call is made.

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?

An output schema exists, so return structure need not be explained, and the description still summarizes the returned sections. For a read-only, single-optional-parameter tool, the definition covers scope, sampling caveat, sibling alternatives, and cost — everything an agent needs to select and invoke it 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?

Schema description coverage is 100% and the single `limit` parameter already documents its meaning and range (1-20, default 10). The description never mentions `limit` or explains that it caps the top client-version and country lists specifically, so it adds no meaning beyond the schema. Baseline 3 applies when the schema does the work.

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 resource (reachable Bitcoin nodes from the latest bitnodes.io snapshot) and enumerates the exact contents: totals, network breakdown (Tor/IPv4/IPv6/I2P/cjdns), top client versions, top ASNs, and countries of the top-100 leaderboard. An agent can distinguish this node-census tool from block, mempool, or transaction siblings without opening the 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 explicitly routes the agent elsewhere for two neighboring needs ('crypto_btc_whale_txs when you need Large Bitcoin transactions', 'crypto_btc_block when you need Detailed Bitcoin block summary') and flags that country data is 'a ranked sample, not all nodes'. It stops short of stating when this tool should be preferred over other Bitcoin network-health siblings like mempool or hashrate tools, so the guidance is clear but not exhaustive.

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