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

Annotations already declare read-only, idempotent, and non-destructive. The description adds a useful behavioral detail: providing a block hash improves reliability for confirmed transactions. No contradiction with annotations.

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?

Two concise, front-loaded sentences with no unnecessary words. Every phrase contributes to understanding the tool's action and a useful tip.

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?

For a simple read tool with rich annotations and schema, the description covers the core functionality and a reliability hint. It doesn't describe the return format or error handling, but given no output schema and the tool's simplicity, this is adequate.

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 coverage is 0%, so the description must compensate. It explains that txid is the identifier and blockHash is optional, adding that blockHash improves reliability. This adds semantic value beyond the schema's patterns but remains minimal.

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 clearly states 'Read a raw Bitcoin transaction by txid' – a specific verb, resource, and identifier. This distinguishes it from siblings like btc_getTxOut (which returns a transaction output) and evm_getTransaction (EVM-specific).

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 provides context that a block hash can make confirmed transaction lookup more reliable, implying when to use the optional parameter. However, it does not explicitly mention alternatives or when not to use this tool, so it's clear but lacks exclusions.

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