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

No annotations are provided, so the description carries the burden. It discloses a key behavioral trait: the tool may be unavailable on some deployments. However, it doesn't mention rate limits, authentication needs, or what happens when the handle doesn't exist or the fetch fails. The availability caveat is valuable but incomplete for a network-fetching 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?

Two sentences, front-loaded with the core action, and the availability caveat is placed second. Every sentence earns its place; no filler or 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?

The tool has an output schema, so return values are covered elsewhere. The description covers the main usage context and a critical deployment caveat. It could add a note about error behavior or authentication, but for a simple fetch tool with a rich schema, it is largely complete.

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%, so the schema already documents all four parameters. The description adds no extra parameter-level meaning beyond the schema, but the schema is self-sufficient. Baseline 3 is appropriate.

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 ('Fetch') and resource ('recent posts for an X (Twitter) handle'), which clearly distinguishes it from generic search tools. It doesn't explicitly name a sibling alternative, but the mention of community_signal / hn_attitude as alternatives helps differentiate it from those social-voice tools.

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 clear context: use this for recent posts by a specific handle, and prefer community_signal / hn_attitude for broad community voice when realtime social fetch is disabled. It doesn't explicitly say 'when not to use' beyond the availability caveat, but the alternative routing is useful and specific.

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