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

Annotations already cover safety (readOnly, non-destructive, openWorld), and the description adds genuinely new behavioral context: the operation costs 2 credits and the tag-count customization is gated behind paid plans. It also notes the return is an array of suggested tags, which helps set expectations beyond the annotation set.

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, front-loaded with the core action and followed by input/output expectations and cost. The only waste is the redundant 'Hashtag Generator: Hashtag Generator' opening, which repeats the title verbatim.

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 simple two-parameter generator with an output schema already describing the return shape, this is nearly complete: it covers input, output type, cost, and the paid-tier constraint on count. The only missing piece is guidance on when to prefer a sibling extraction tool instead.

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 baseline is 3, but the description adds real meaning the schema does not carry: the count parameter's customization is a paid-plan capability, and the input can be 'any plain text or post caption.' That framing tells the agent what content types work well without contradicting the schema's 1-10 range.

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 states a specific verb and resource: it 'creates relevant hashtags from any plain text or post caption' and returns an 'array of suggested social tags.' That is unambiguous, though it opens by redundantly restating the name/title and never contrasts itself with nearby siblings such as KeywordExtractor or TexttoEmoji.

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?

Usage is implied through 'Pass in a text snippet,' which tells the agent the expected input shape but not when to choose this tool over alternatives. There are no explicit preconditions or exclusions, so the agent must infer applicability from the purpose statement alone.

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