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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real value beyond that by disclosing the returned content sections, which matters because there is no output schema. It does not cover failure behavior for an unknown slug or any truncation/access limits.

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: the first front-loads what the tool returns and the second gives the calling instruction. The section enumeration is long but earns its place given no output schema exists. Minor awkwardness in "the upside and downside the story names" is the only drag.

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 one-parameter read tool with annotations and no output schema, the description covers purpose, input provenance, and return content, which is the right set of things to explain. Only edge-case behavior (invalid slug, partial access) is left out.

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 100% for the single parameter, and the schema text ("The story url or slug from another tool") already states both accepted forms. The description only adds the specific provenance tools, which is marginal over the schema. Baseline 3 is appropriate.

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 names the specific resource (the full NewsStocks.live write-up of one story) and enumerates exactly what it contains: summary, take, key numbers, watch-next, background, upside/downside. That clearly separates it from latest_news and search_news, which surface stories rather than expanding one. It stops short of a clean leading verb phrase, but the noun phrase is unambiguous.

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?

"Pass the url or slug from latest_news or search_news" tells the agent both the precondition (you already found the story elsewhere) and the exact sibling tools that supply the input. It does not state exclusions or when a lighter-weight sibling would be preferable, but the routing context is concrete rather than implied.

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