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

Annotations already declare this as a read-only, idempotent, open-world, non-destructive operation, so the safety profile is well-covered. The description adds minimal behavioral context beyond that; it doesn't specify return format, pagination, or any special behavior regarding unconfirmed balances or error conditions. Given the annotations, a 3 is appropriate as no contradictions exist, but the description doesn't enrich the behavioral picture significantly.

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 one concise sentence with no wasted words. It is front-loaded with the action and resource, making it easily scannable.

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?

The tool is simple with one parameter, and the schema provides full parameter details. However, there is no output schema, so a brief mention of what the response contains (e.g., list of rune balances with amounts) would improve completeness. Annotations cover the behavioral safety aspects, and the description succinctly states the purpose, so it is adequate but not thorough.

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 schema covers 100% of the parameter documentation, with bitcoinAddress described as 'The Bitcoin taproot address to check rune balances for'. The description adds no extra semantics beyond the schema, aligning with the baseline 3 for high schema coverage. The parameter is simple and well-documented by the schema.

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 states a specific verb ('Get') and resource ('Rune token balances'), clearly indicating it retrieves Rune balances for a user. It could potentially be confused with getUtxoRunes or getRuneInfo, but the focus on 'user's' balances, singular address input, and the title prefix helps distinguish it from general rune info or UTXO-specific queries, though it does not explicitly name alternatives.

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 description implies usage for checking a user's rune balances given a Bitcoin address, and the schema requires bitcoinAddress. However, it doesn't explicitly state when to use this versus similar tools like getUtxoRunes or getRunesActivity, nor does it provide exclusions or alternative tool recommendations.

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