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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description still adds real behavioral context beyond that: a fixed cost of 10 credits and concrete output limits (up to 50 keywords, counts, total volume, top five with percentage share). It omits failure behavior for unreachable URLs, which keeps it below a 5.

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 purpose and then payoff and cost, with no filler. The leading 'Keyword Extractor: Keyword Extractor is...' prefix redundantly restates the name and title, which is the only clear waste.

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 two-parameter extraction tool with full schema coverage, annotations, and an output schema, the description covers inputs, result shape, and cost adequately. The only gap is guidance on selecting between the url and text parameters and what happens on fetch failure.

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 carry descriptions plus examples, so the schema does the heavy lifting and baseline 3 applies. The description reinforces the url-vs-text duality but adds no rule about mutual exclusivity or which one is expected given that neither parameter is required.

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?

States a specific verb and resource ('extract key terms and their frequencies') and names both accepted inputs (raw text or live webpage URLs), so an agent knows what the tool does. It does not distinguish itself from nearby siblings such as TextSummarizer, WordLexiconAnalyzer, or PartsOfSpeech, which also operate on text and return linguistic analysis.

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 only implied: the description says it accepts text or a URL, which hints at the two modes, but it never says when to prefer this over sibling text-analysis tools or whether exactly one of text/url must be supplied. No exclusions or prerequisites are stated.

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