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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description adds nothing beyond that: it never mentions that this call may incur a cost (the max_sats parameter exists precisely because the call can charge sats) or any rate/limit behavior, which is the kind of context that would justify its presence.

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 short, front-loaded sentences with no filler — the resource is named first and the batching note follows. Slightly redundant with the schema's own pubkeys description, which keeps it from a 5.

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 no explanation, and parameter semantics are fully covered by the schema. What is missing for an agent to call this safely is the commercial/behavioral context — that a non-read-only, non-idempotent call may charge up to max_sats — plus any routing versus sibling tools.

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 description coverage is 100%, so the schema already explains pubkey, pubkeys, the 02/03 prefix pattern, the 10-item cap, and max_sats charging semantics. The description only restates the pubkeys batching limit, adding no meaning beyond the schema; baseline 3 is appropriate.

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 verb-noun pair ('Lightning node snapshot by pubkey') and the identifying resource (pubkey), which is enough for an agent to know it returns node data. It does not, however, distinguish itself from nearby siblings like lightning_liquidity or balance, so an agent must infer which node-related tool to pick.

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?

'Pass pubkeys (up to 10) for one call' gives a batching hint, which is implied usage guidance for the array form. There is no statement of when to use this versus lightning_liquidity or balance, and no prerequisites or exclusions are given.

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