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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the read-only nature is covered structurally. The description adds useful behavioral context by enumerating the returned fields and noting that multiple IDs are accepted per call. It does not discuss edge cases like invalid IDs or rate limits, but those are minor for a read-only fetch with an output schema.

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 sentences with no filler: the first states the core function, the second adds contextual use case, the third names the fallback tool. Every sentence earns its place and the purpose is front-loaded.

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 tool with one required parameter and an output schema, the description covers input, return content, use case, and the alternative when not to use it. An agent has everything needed to decide whether to call it or choose the search sibling instead.

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 schema only defines tweet_ids as an array of strings, with a terse property comment. The description adds that the IDs must be numeric and that multiple IDs can be supplied in one call, which clarifies how to construct the parameter. The lone schema wrinkle is 'comma-separated' vs the array type, but the description itself does not introduce that ambiguity.

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 opens with a specific verb and resource: 'Fetch the full content of specific tweets when you already know their numeric tweet IDs.' It also clearly distinguishes itself from get_twitter_tweet_advanced_search by framing this as the ID-based lookup versus search. No ambiguity about what this tool does.

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?

It states exactly when to use it: when IDs are already known and you want to expand IDs from search, timelines, or replies into complete objects. It also gives an explicit alternative: 'If you do not have IDs yet, start with get_twitter_tweet_advanced_search.' This is clear when/when-not guidance.

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