x_timeline

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

Annotations already cover safety (read-only, idempotent, non-destructive), and the description adds a useful behavioral detail: it validates the English tab label and fails rather than silently reading the wrong tab. This fail-fast behavior and UI dependency go beyond the structured metadata.

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 short sentences with no filler; the core purpose is front-loaded and the safety/validation caveat is placed second. Every sentence 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 read-only tool with no output schema, the description gives the essential target and a useful failure behavior, but it omits what the returned timeline data looks like and what limit/maxScrolls actually control. An agent can start using it but may mis-estimate pagination or result size.

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 0%, so the description should define parameter meaning. It only partially maps to the tab parameter by naming 'Following or For you'; limit and maxScrolls are never explained, leaving their behavior to inference from names and schema defaults.

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 states a specific verb ('Read') and a specific resource ('Following or For you home timeline'), which clearly distinguishes it from sibling tools like x_user_posts or x_notifications. The tab selection is named explicitly, so an agent knows exactly which view this tool targets.

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 implies the tool is for reading the user's home timeline and contrasts the two tab options, but it does not explicitly state when to choose this over sibling read tools like x_search or x_user_posts. There is no when-not-to-use guidance beyond the English-label caveat.

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