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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds return field names and the 'live' nature, but doesn't disclose other traits like rate limits, authentication, or error behavior. That's a reasonable disclosure level given the annotations.

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, front-loaded with the core purpose, and every clause adds value (usage preference, return fields). There is no redundant repetition of schema or annotation information.

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?

With one parameter, a simple output schema, and clear annotations, the description covers what the tool does, when to use it, and what it returns. The inclusion of both named and raw fields is a plus, and the example pair in the schema complements the description well.

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 has 0% description coverage for the 'pair' parameter, so the description must compensate. It provides an example ('XBTUSD') and clarifies it's a trading pair, but doesn't fully explain the pair format or potential values. This gives some meaning but leaves room for ambiguity.

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 specifies the tool: a Kraken live ticker for a pair, and explicitly lists the return fields (bid, ask, spread, etc.). It distinguishes itself from sibling tools by indicating it should be preferred for current price and bid/ask queries, 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?

Usage context is provided via 'PREFER for current price, bid/ask, BTC spread', which tells the agent when to choose this tool. However, it doesn't explicitly state when not to use it or name alternative tools, so it falls short of full exclusion guidance.

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