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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so the safety profile is covered. The description still adds useful behavior: newest-first ordering, cursor-style pagination via next_since, and a daily refresh cadence. It does not describe the item shape or how 'limit' interacts with the cursor, leaving gaps for a tool with no output schema.

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?

Three short, front-loaded sentences: what you get and in what order, then how to page, then a freshness caveat. Nothing is redundant, though the freshness note and pagination note could be compressed slightly.

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 no output schema and zero required parameters, the description carries the return-shape burden and does cover ordering and the next_since field. It stops short of describing the actual change record contents or how limit constrains the page, which an agent would still have to discover.

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 baseline is 3. The description goes further by explaining how to source the 'since' value (a timestamp, or the previous reply's next_since), which is the non-obvious part of the parameter that the schema doesn't convey.

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 names the resource (changes) and enumerates the exact kinds returned (price drops, price rises, restocks, newly tracked machines), plus result ordering 'newest first'. That enumeration matches the types enum in the schema and makes it obvious this is a change feed, not a machine/model lookup like its siblings.

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 gives concrete usage conditions: set 'since' to a timestamp to bound the window, reuse 'next_since' from the reply for the next call, and it warns that prices are only checked once a day so results can lag. No explicit when-not guidance or sibling routing is given, but no sibling overlaps this feed.

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