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

With no annotations, the description carries the full burden. It does add behavioral value by stating the result order is newest-first and that pagination uses before_id. It does not explicitly state read-only behavior, error conditions, or return shape, but those are partially inferable for a simple list tool.

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 extremely concise: the first clause states what the tool returns and the ordering, and the second clauses states how to paginate. Every word earns its place with no filler or schema repetition.

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 feed-item listing tool, this is minimally adequate: it identifies the feed, the ordering, and the pagination mechanism. However, with no output schema, it does not describe return values, and the sibling context suggests it could benefit from clarifying when to use it instead of recent_items or search_items.

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 adds little beyond the schema: before_id is already labeled as a keyset cursor, limit has a default/max, and feed is described as a slug. No additional parameter semantics are provided.

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 identifies the resource as feed-selected items and specifies the ordering as newest-first. It does not use an explicit verb like 'list' and does not name sibling tools, but it is semantically clear enough to be distinguished from list_feeds, recent_items, and get_item.

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 description provides no guidance on when to use this tool versus recent_items, search_items, or get_item. The pagination hint is operational rather than a usage rule or alternative-selection guideline.

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