check_favorite_price_drops

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

With no annotations, the description carries the full burden. It discloses the stateful side effect of recording prices and the fact that results depend on prior calls. It does not mention any further side effects (e.g., network calls or modifying favorites), but the disclosed behavior is clear and non-contradictory.

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 sentences with no waste. The primary action and output format are front-loaded, followed by the essential usage caveat. Every word earns its place.

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 parameterless tool with an output schema, the description provides everything needed: the action, the return structure, and the statefulness caveat. An agent can invoke it correctly without further clarification.

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 tool has zero parameters, so the baseline is 4. The description adds no parameter-specific detail because none exist; the schema already covers the empty property set.

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 uses a specific verb 'Record' and resource 'favorites prices', and clearly states the output diff with fields {drops, rises, added, removed}. This distinguishes it from siblings like list_favorites (listing) and set_favorite (modifying), leaving no ambiguity about its function.

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?

It explicitly advises 'Call it periodically' and explains the consequence: 'the comparison is only as old as the previous call.' This gives clear when-to-use guidance, though it does not mention alternatives or when not to use it, which are not necessary given the unique role among siblings.

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