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

No annotations are provided, so the description carries the full behavioral burden. It only discloses that titles are discarded, but it does not state whether a live network fetch occurs, what the return value looks like, how failures are handled, or which of the nine declared inputs are actually used. This leaves too much unspecified.

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 two short sentences, front-loads the core action, and contains no filler. 'Titles discarded' is a compact and useful clarification that earns its place.

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 nine optional parameters, no output schema, and no annotations, so the description should explain how to invoke it and what result to expect. It only says to count HN stories and discard titles, never stating whether any parameter is needed, which one, or what the count response looks like. The generic input schema makes this omission especially confusing.

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 describes all nine parameters, so the baseline is 3. The tool description adds only 'Titles discarded,' which largely echoes the feed parameter's schema description and does not clarify why unrelated parameters like city, zone, or json exist or which parameter should be supplied for the HN count.

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 uses a specific verb and resource: 'Count current Hacker News front-page stories.' It also adds a delimiting behavioral note, 'Titles discarded,' which clarifies that the result is a count, not story content. This clearly distinguishes it from sibling fetch and shape-checking 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 provides clear context: this is the tool for counting current Hacker News front-page stories. It does not explicitly name alternatives or exclusions, but no sibling tool appears to overlap with this purpose, so the context is sufficient for an agent to know when to select it.

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