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

Annotations already signal read-only and non-destructive behavior. The description adds valuable context beyond those annotations: cost per poll via x402, credit-based alternative, newest-first ordering, and that it returns structured items. This goes meaningfully beyond the structured annotation data.

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?

Three sentences carry the core use case, the exclusion of arbitrary URL reading, return ordering, and cost. It is front-loaded with the primary trigger and every sentence earns its place without redundancy.

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 read-only list tool with two well-documented parameters and rich annotations, the description covers selection, cost, ordering, and exclusions. Since there is no output schema, 'returns structured items, newest first' is the only gap, but it is minor for an agent deciding whether to call this tool.

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 description coverage is 100%, and both parameters are already well-documented with types, enums, default, and minimum. The description reinforces the feed concept and references named feeds but does not add parameter-specific meaning beyond 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 clearly states a specific verb and resource: fetch the latest items from a curated signal feed, not a one-off URL. It explicitly distinguishes itself from skim_read and skim_extract, so an agent can select it 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 gives explicit when-to-use guidance ('when you need the latest items from a curated intel feed'), recommends it over crawling news homepages, and explicitly warns against using it for arbitrary URLs by naming skim_read as the alternative.

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