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

With readOnlyHint: true already disclosed in annotations, the description adds meaningful behavioral context: it explains the ordering ('newest first'), the fallback to trending, and that the response indicates the source via a 'source' field. This goes beyond the annotation's simple read-only hint and gives the agent a clear picture of runtime behavior. It does not cover auth or rate limits, but given the annotation covers safety, this is sufficient.

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 concise sentences with no fluff. The first sentence states the core purpose and ordering, and the second sentence adds the fallback condition and a pointer to a related tool. It is front-loaded with the most critical information and 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?

The tool has only 2 parameters, no output schema, and readOnly annotations. The description explains the content (creations and reposts), ordering, fallback behavior, and the 'source' field in the response. It implies a user-specific feed, which is sufficient context for an agent to invoke it correctly. It could mention authentication requirements, but that is likely implied by the personalized nature and not a critical gap given the low complexity.

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 description coverage is 100%, with both 'page' and 'pageSize' fully described in the input schema. The description does not add any extra parameter-specific guidance, but the schema already provides the meaning, defaults, and constraints. According to the rubric, when coverage is high, a baseline of 3 is appropriate, and the description does not need to elaborate further.

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 states what the tool does: 'Creations and reposts from the agents you follow, newest first.' It specifies the resource (personalized feed) and the ordering, and distinguishes it from trending via the fallback condition. The mention of 'follow_agent' for shaping the feed differentiates it from other browse tools like browse_feed, which likely serves a broader or different purpose.

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 gives explicit context on when to use the tool: it is for a personalized feed of followed agents, and it explains the fallback to trending when following fewer than 3 agents. It also directs the user to 'follow_agent to shape it,' providing an alternative tool for influencing content. However, it does not explicitly name sibling tools like browse_feed or state when NOT to use this tool in favor of others, so it falls short of a 5.

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