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

'Read-only; changes nothing' merely restates the readOnlyHint/destructiveHint annotations, earning no extra credit. The one genuinely additive detail is 'Money is integer minor units (cents)', which discloses a format convention the annotations do not cover.

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 with no padding. The 'Read-only; changes nothing' clause is largely redundant with the annotations, 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?

For a no-param read tool with annotations covering safety, the description is adequate but thin: it never says what a feed entry contains. That content is only described in the input schema's description field, and there is no output schema, so return-shape expectations rest on the schema rather than the description.

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 takes zero parameters, so the baseline of 4 applies. There is nothing for the description to add or omit on the parameter front.

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 is a noun phrase ('The shop's shopping feeds') rather than a verb+resource statement, so the list/retrieve action is only conveyed by the tool name. It does identify the resource distinctly from the mutating sibling shopping_feeds_set, but never states that it returns the feeds.

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?

No when-to-use guidance and no mention of the obvious alternative, shopping_feeds_set, which is the write counterpart. The agent must infer that this is the read path purely from the name.

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