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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds genuinely new operational context: a required TAOSTATS_API_KEY and a per-call cost of $0.002 USDC via x402 with failed calls not charged. Those cost and credential facts materially affect whether an agent should call it, which is exactly the kind of information annotations cannot carry. It stops short of disclosing rate limits or latency 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?

The lead sentence front-loads the resource and the fields returned, and the credential/price sentence is compact and useful. The sibling routing clause uses a repetitive formulaic construction ('Related tools on this server, for a different need: X when you need ..., Y when you need ...') that costs more words than necessary, though nothing is truly wasted.

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 values need not be explained, and annotations cover the safety profile; the description fills the remaining critical gaps of authentication and pay-per-call cost. The only omission relative to complexity is that the single tunable parameter and its default are not mentioned, a minor gap for a low-complexity read 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?

Schema description coverage is 100% for the single optional 'limit' parameter (1-100, default 20), so the schema fully documents it. The description never mentions the limit or what it controls, so it adds no meaning beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 opening sentence names a specific resource and measurement: Bittensor subnet registration (burn) cost trajectory, current burn cost in TAO, recent block history, min/max, and timestamps. It also explicitly distinguishes itself from two named siblings that return different subnet data, so an agent can route without opening either 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 names two alternatives (crypto_tao_subnet for detailed pool metrics, crypto_tao_subnet_concentration for stake/emission concentration) with the condition that selects each, which is strong routing guidance. What's missing is an explicit positive statement like 'use this when you want historical burn cost across blocks' or any exclusion about when not to call it.

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