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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds valuable context by stating 'Uses exact whole-satoshi integer maths' (precision guarantee) and providing the conversion factor (1 BTC = 100,000,000 satoshis), plus a source URL. This goes beyond annotations without contradicting them.

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 description is two sentences: the first states the core function, the second adds precision details and a source link. It is front-loaded and every sentence earns its place with no wasted words.

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 two-parameter converter with full schema coverage and an output schema, the description provides all necessary context: the conversion directions, the units involved, the integer precision, and the conversion rate. It does not explicitly mention handling of fractional BTC amounts, but the schema's 'BTC amount' implies that, and the output schema covers return format.

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 100% and both parameters are described. The description adds meaning by clarifying that conversions include mBTC and bits, and that the tool uses exact integer maths, which informs how the 'value' parameter should be interpreted (whole satoshis vs BTC amounts). This goes slightly beyond the schema's bare parameter descriptions.

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 a specific verb ('Convert') and a specific resource ('satoshis to BTC, mBTC and bits'), and explicitly names both conversion directions. It distinguishes itself from sibling unit converters by focusing on Bitcoin units, making its purpose unambiguous.

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?

The usage context is implied rather than explicit: if you need Bitcoin unit conversion, this is the tool. It does not mention alternatives or exclusions, but the name and description make the use case obvious. For a simple converter, this is adequate but not exemplary.

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