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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful context beyond that: the exact confirmation-target grid, the named recommended fields, the mempool floor, and the Zcash cross-reference, though it does not mention caching/rate-limit or freshness characteristics.

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?

Front-loaded with the core purpose, then cleanly segmented into when-to-use, do-not-use, and returns. Despite its length, every clause carries distinct information (target list, field names, sibling routing) 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?

There is no output schema, so the description compensates by enumerating the returned fields and units (BTC/kvB, sat/vb for the named recommended fields). Combined with the routing guidance, an agent has everything needed to call 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. The 'Returns' prose is about output rather than input, which is helpful but not parameter semantics.

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 resource (Bitcoin fee rates) and scope (confirmation targets plus mempool floor) with a clear read verb implied. It explicitly distinguishes itself from btc_get_mempool_state and from Zcash fee handling, so an agent can identify it among siblings without opening a 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?

Gives explicit when-to-use ('pricing a Bitcoin transaction, or deciding when a sweep will confirm cheaply') and an explicit when-not-to-use that names the correct alternative ('to measure backlog depth ... that is btc_get_mempool_state'). It also pre-empts a wrong-chain assumption by noting ZEC fees are protocol-fixed.

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