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

With no annotations, the description carries the full burden and does an excellent job. It discloses that this is a real charged transaction, settles through a mandate-checked payment path, requires a funded wallet, and describes the failure behavior (no summary, no charge). This goes far beyond the schema and provides vital behavioral context.

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?

The description is four sentences, somewhat longer than strictly minimal, but every sentence adds value: explaining the paid nature, the return type, when to use, and failure conditions. It is front-loaded with the core purpose and remains readable.

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?

Given that this is a paid transaction tool with no annotations and no output schema, the description is remarkably complete. It covers the payment side effects, prerequisites (funded wallet), failure behavior, and usage guidance, making it sufficient for an agent to select and invoke the tool correctly.

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. The description adds little parameter-level detail beyond what the schema already provides; it mentions 'any block of text' and 'concise extractive summary' but does not elaborate on max_sentences or other parameter semantics. The schema already documents both parameters adequately.

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 the tool purchases a real, paid text-summarization service and returns a concise extractive summary. It uses a specific verb ('purchases') and resource ('text-summarization service'), and distinguishes this from siblings by emphasizing it is a paid marketplace transaction rather than a free utility.

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?

Explicitly directs use 'whenever the user asks you to summarize, condense, or buy/purchase a summary of some text using your Focxle tools.' It offers clear context, but does not mention when not to use it or provide alternatives, so it falls short of a full 5.

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