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

No annotations are provided, so the description carries the behavioral disclosure burden. It conveys that the operation is a read-only listing and that returned sources include reliability/reputation and category. It does not cover pagination, sorting, or result shape, but for a simple listing tool this is reasonably transparent.

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 a single concise sentence that leads with the verb and object. There is no filler or redundant restatement of the tool name, despite minor awkwardness in 'reliability(reputation)'.

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 optional parameter and no output schema, the description covers the main need: what the tool lists and what kind of data is included. It is brief on output shape, but the low complexity and the schema's parameter documentation make this adequate.

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 input schema already documents the only parameter with 100% coverage ('optional category filter'). The description mentions category but adds no additional meaning about accepted values, behavior, or how the filter interacts with the listed sources, so it stays at the baseline.

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 ('List') and resource ('data sources in QY Stream'), and adds what is included (reliability/reputation and category). It is clear on its own, though it does not explicitly contrast itself with the sibling tools qy_fetch_articles and qy_search_news.

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?

There is no guidance on when to use this tool versus the siblings. The description only says what the tool does, not when an agent should prefer qy_list_sources over qy_fetch_articles or qy_search_news.

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