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

Annotations already mark the tool as read-only, idempotent, open-world, and non-destructive. The description adds valuable behavioral context beyond that: data is fetched live on every call, nothing is stored, and a plan-limit message is returned on rate limiting or quota exhaustion. No contradiction exists.

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?

Four short sentences, each earning its place: the core purpose, live-fetch behavior, usage context, the sibling differentiator, and the rate-limit behavior. Information is front-loaded and no words are wasted.

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 three-parameter read-only tool with no output schema, this description is complete enough for an agent to select and invoke it correctly. It covers when to use it, what it returns conceptually ('top posts'), live behavior, storage, and error signaling. The missing structured return details are not necessary for invocation.

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 clear parameter documentation for keyword normalization, valid sources, and the limit bounds/default. The description adds broader context about one hashtag and one source but does not meaningfully enrich individual parameter semantics beyond the schema.

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-resource pair: 'Live top posts for one hashtag on one social source.' It clearly distinguishes itself from the sibling by stating 'get_top_trends ranks the hashtags themselves,' so an agent can tell the two tools apart.

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 explicitly states when to use the tool: 'when the user already has a hashtag and wants the posts winning on it.' It also names the closest alternative and what that tool does instead, giving clear selection guidance.

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