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

Annotations declare non-read-only, non-idempotent, non-destructive, closed-world, but the description adds genuinely new behavioral context: one card per headline, public immediately, no fee, nothing traded, and a paid-plan auth gate. These side-effect and cost details are exactly what annotations don't convey; only the 'one card per headline' wording slightly rubs against idempotentHint=false, but not enough to be a contradiction.

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?

A single dense sentence that front-loads the API context and the read-mode purpose before the write mode. It is information-rich and mostly free of filler, though the parenthetical of behavioral notes is packed tightly enough to need a second read.

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 compensates by enumerating the possible status returns and stating the auth prerequisite and side effects. Complete enough to invoke correctly, though it does not mention what happens on a refused/pending headline when make=true is passed.

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%, so the baseline is 3, but the description goes further by naming the possible status values (exists/pending/refused/not_requested) and explaining what make=true triggers via the card pipeline. It adds semantic depth beyond the schema's terse 'true to make the card if none exists'.

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 (Event Card status of a headline) and its two modes — read status vs. create with make=true — using a concrete verb+resource. An agent can distinguish this from search_headlines_api and preview_card_basket without opening the schema.

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?

It explicitly states the branch condition for the write mode ('with make=true, make one') versus the default read mode, and flags the prerequisite ('Needs a paid NEXUS plan'). It stops short of naming an alternative tool (e.g., preview_card_basket) for the related use case, so it is clear but not fully routing-aware.

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