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

Annotations already cover the important safety profile (readOnlyHint, idempotentHint, destructiveHint). The description adds that the values are 'effective' and 'x1' probabilities, adding slight context, but it doesn't explain what 'effective' means or what the response contains.

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?

A single, front-loaded sentence with no filler. Every word contributes: the operation, the resource, the rate type, and the required input scope.

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-only lookup with two required parameters, the description is nearly sufficient: it states the exact data returned and the input requirement. It could also mention the role of chronicle or the return shape, but the low complexity keeps this gap minor.

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 0%, so the description must compensate for parameter meaning. It clarifies npcId by saying 'one numeric NPC ID', but it gives no explanation of the required chronicle parameter or how it affects the probabilities. This is only partial compensation.

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?

Clear verb+resource: 'Get effective x1 drop and spoil probabilities' for a specific NPC ID. It is precise and obviously distinct from siblings like get_npc or search_npcs, but it never explicitly names or contrasts itself with them.

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 phrase 'for one numeric NPC ID' implies the intended use: when you already have a known NPC ID and need drop/spoil rates. It provides no explicit alternatives or when-not-to-use guidance, so usage is only implied rather than stated.

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