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

The description adds real behavioral context beyond annotations: calls are billed against the credit balance and priced at roughly 1 sat ≈ $0.0008. That explains why readOnlyHint=false despite the read-like nature (the call spends money). It does not disclose latency, caching, or failure/refund behavior in a paid context.

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?

It is short and front-loaded, but 'Paid from the credit balance' is stated twice in slightly different words, wasting one of only four sentences. The redundancy signals padding rather than precision.

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 spelled out, but this tool has three distinct query modes (quote, offer_book, node) with different semantics and a paid-spend model, and the description explains none of the mode differences or billing edge cases. Given that complexity, it is under-specified.

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%, so the enum values and max_sats/connection_uri semantics are already documented in the schema. The description adds no parameter meaning at all, so the baseline 3 applies.

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 offers a marketing tagline ('Structured live Magma data in one call') rather than a specific verb+resource statement. It never says what Magma is, what the three query modes return, or how it differs from close siblings like magma_buy or lightning_liquidity.

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?

'No Node or GraphQL setup' hints at an alternative to self-hosting, and the credit-balance mention implies a paid call, but there is no explicit when-to-use, when-not-to-use, or sibling routing. An agent choosing between magma_liquidity, magma_buy, and lightning_liquidity gets no help here.

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