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 fully covered. The description adds one genuinely new behavioral fact not in the schema: omitting id silently defaults to the newest post, which is important to know. It says nothing about invalid-id handling or return shape, so it adds value without being rich.

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 short sentences with no filler. The core purpose is front-loaded and the parameter guidance and default behavior follow in the order an agent needs them.

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 single-optional-parameter read tool with no output schema, the description covers purpose, input source, and default behavior — enough to call it correctly. The only real gap is error behavior for an unknown id, which is minor at this complexity.

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 0%, so the description carries the full burden for the single parameter, and it does: it identifies where the id comes from (news_list) and what happens when it is omitted, which the bare integer schema cannot convey. It does not mention that id must be a positive integer, but the source hint is the higher-value information.

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?

Names the resource and scope precisely: 'the full text of one news post,' which distinguishes it from the sibling news_list that returns many. It is a noun phrase rather than a verb-led statement, but the read intent is unmistakable and the singular-vs-list contrast with news_list does the differentiation work.

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?

Explicitly routes the agent: 'Pass the id from news_list,' naming the sibling that produces the input. It also states the no-argument path ('without one, the newest post'), so both call modes are covered. It stops short of stating when-not to use this tool, but the context is clear.

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