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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that titles are discarded and that the count reflects 'current' content, but it does not explain whether this involves a live network fetch, potential rate limits, error behavior, or which inputs are actually consumed.

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 extremely concise and front-loaded with the core action. The second sentence, 'Titles discarded,' earns its place by clarifying a likely ambiguity about whether story titles are returned.

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?

Given the tool has 9 optional parameters and no output schema or annotations, the description is not complete enough. It never connects the parameters to the operation, states whether any input is required, or describes the return value beyond the implied count. An agent would be uncertain whether to call this with no arguments, with a feed URL, or with some other parameter.

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 baseline is 3. Every one of the 9 parameters has its own description in the schema. The tool description adds no additional parameter-level meaning and does not clarify which of the optional parameters, if any, are relevant to counting Hacker News front-page stories.

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 and resource: 'Count current Hacker News front-page stories.' It clearly identifies what the tool does and is distinguishable from sibling counting tools like memory-key-count and search-query-len. The phrase 'Titles discarded' adds a scope clarification, though it is more behavioral than purpose-related.

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 no explicit guidance on when to use this tool versus alternatives like web-fetch or memory-key-count. 'Titles discarded' implies the tool should not be used if titles are needed, but it does not name alternative tools or provide selection conditions.

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