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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so the safety profile is covered. The description adds a genuinely useful behavioral caveat the annotations cannot convey: bodies over 100,000 characters are truncated, and a note marks the truncation, which matters for an agent relying on full-text fidelity. It does not describe the not-found/error behavior, keeping it out of 5 territory.

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?

Two sentences, both front-loaded with the essentials: what is returned first, then the truncation caveat. Nothing is redundant with the title or the annotations.

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?

With no output schema, the description usefully sketches the return shape ("metadata and full text") and the truncation limit. The remaining gap is call-edge behavior: an agent cannot tell from the definition what error results from a missing or unknown slug/URL.

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 coverage is only 50% (the url parameter is documented in-schema, slug is not), so the description has to carry additional weight. It establishes that slug and URL are alternatives for lookup, but does not state precedence when both are provided, nor that zero parameters are required – leaving real 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 uses a specific verb and resource ("Returns one theaftermath.news post with its metadata and full text") and names the two lookup keys, so it is clearly a single-post fetch rather than the bulk operations in latest_news or search_news. It stops short of naming those siblings explicitly, which is why it doesn't reach 5.

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?

"looked up by slug or by URL" implies the retrieval contexts in which this tool applies, and the contrast with the list/search siblings is inferable from "one post". However, there is no explicit statement of when to prefer this over search_news, nor of what happens when neither or both keys are supplied.

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