keyword_difficulty

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

With no annotations present, the description carries the full burden and does disclose the critical behavioral trait: a paid call costing 0.05 USDC on Base via x402. It also implies a compute/read operation rather than a mutation. It does not mention latency, caching of repeat requests, or rate limits, which is a modest remaining gap.

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 front-loaded line: purpose first, scope second, cost last. No filler, nothing to trim.

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 4-parameter, no-output-schema tool the description covers what it produces (a 0-100 score per keyword) and the payment requirement, which is the main thing an agent could get wrong. Output shape beyond the score, and the retry/billing nuance hinted at by confirmNewPurchase, are left to the schema.

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 75% and the description reinforces two key semantics — the 1000-keyword cap and the 0-100 output scale. The one gap is language_code, which has no description in either the schema or the description; otherwise parameter meaning is well covered.

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?

Specific verb+resource (SEO ranking difficulty score) with an explicit numeric scale (0-100) and scope (up to 1000 keywords), plus a plain-language restatement ('how hard it is to rank on Google page one') that separates it from sibling metric/volume tools like keyword_metrics and ai_search_volume.

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?

No explicit when-to-use or when-not-to-use statement, and no alternatives named among the many keyword siblings (keyword_metrics, keyword_ideas, keyword_gap). The cost disclosure (0.05 USDC per call) is useful practical context that implicitly frames it as a deliberate, paid lookup, but the agent must still infer selection criteria.

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