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

Goes well beyond the annotations: it discloses the cost model ('$0.003/call via x402 USDC or a card key'), the failure policy ('failed calls free'), auth mechanics, and that repeat calls are billed ('each call is charged, so repeats are not free'). This is exactly the kind of context annotations cannot carry, and it is consistent with idempotentHint=false.

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?

Four dense sentences, front-loaded with what the tool does before limits, pricing, and safety notes. Every clause carries actionable information; nothing is padding.

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?

With no output schema, the description does describe the return content ('a few sentences plus bullet key points'), and it covers cost, auth, and side-effect profile. It stops short of describing the actual response format (e.g. JSON field names), which is a minor gap for an output-schema-less 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%, so both parameters (text, sentences) are already documented with limits and the default of 3. The description repeats the 12,000-character cap but adds no new meaning beyond the schema, so the baseline 3 applies.

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+resource ('Summarize ... text you send') and specifies the output shape ('a few sentences plus bullet key points'), which distinguishes it from siblings like ai_outline, ai_keywords, and ai_rewrite. The character cap makes the scope concrete.

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?

Gives explicit use cases ('long emails, documents, transcripts and tool outputs') and an explicit routing exclusion ('for a web page by URL, use /summarize'). An agent can decide when to call this versus the URL summarizer without further inference.

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