pdfzen

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

Annotations already indicate readOnlyHint=true, and the description adds 'Free, no payment, no auth required', clarifying cost and authentication. It also specifies the exact data returned, further ensuring the agent knows the tool is safe and non-destructive. No contradiction with annotations.

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?

Two sentences, no filler. The first sentence immediately states purpose and return values; the second provides usage context. Every word earns its place, and the key information is front-loaded.

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?

The tool has low complexity (1 parameter, no output schema, no nested objects), and the description fully covers purpose, return contents, usage scenarios, and additional context (free, no auth). No gaps remain.

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 provides 100% coverage for the single 'slug' parameter with description and examples. The description adds a suggestion to call list_starters to discover all 45 slugs, which is valuable context but not critical since schema already gives examples. This slightly exceeds the baseline of 3.

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 uses the verb 'Fetch' and specifies the resource ('starter template by slug') and return contents ('full HTML body, CSS, sampleData, and pageOptions'). It clearly differentiates from sibling tools like list_starters (which lists all) and render_template_to_pdf (which renders).

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 states when to use: before calling render_template_to_pdf to understand the data shape, or to fork a starter. Also mentions it's free and requires no auth, which guides usage context. No explicit when-not statements, but the positive guidance is strong.

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

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

Annotations already declare readOnlyHint=true, and the description adds additional behavioral context: 'Free, no payment, no auth required.' It also describes the return structure as an array with fields, which is beyond what annotations provide. No contradictions.

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 a single paragraph of four sentences, each earning its place: listing templates, specifying return fields, stating free/no auth, and providing a call sequence. No redundancy or filler. Front-loaded with purpose.

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 the tool has no parameters, no output schema, but annotations indicate a safe read operation, the description fully covers what the tool does, what it returns, and how it fits into a workflow. No gaps remain.

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?

The input schema has zero parameters (100% coverage trivially). The description does not add parameter meaning but provides context about the return value and usage flow. According to rubric, baseline for 0 parameters is 4, and the description adds value beyond schema (though not param-specific), so 4 is appropriate.

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 lists 45 public starter templates with specific categories (invoices, receipts, etc.). It uses a specific verb ('list') and resource ('pdfzen's public starter templates'), and distinguishes from siblings by recommending a call sequence including get_starter and render_template_to_pdf.

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?

Explicit usage guidance: 'Call this first to discover what fits the user request, then optionally call get_starter to see the expected data shape, then call render_template_to_pdf to produce the PDF.' This clearly instructs when and in what order to use the tool relative to siblings.

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

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

Beyond annotations indicating non-read-only and open-world, the description discloses the exact payment mechanism ($0.006 per render via x402 USDC), the required header, and the consequence of missing payment, giving full behavioral transparency.

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?

Description is concise with three sentences plus a bolded payment note; every sentence adds value and no extraneous text.

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 tool with nested parameters and no output schema, the description adequately covers input purpose, output format (base64 PDF), cost, and error handling, leaving no critical gaps for an AI agent.

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. The description adds no significant parameter-specific meaning beyond what the schema already provides; the note about Handlebars helpers in the html parameter description is already part of the schema.

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 it renders Handlebars HTML to PDF, and explicitly distinguishes from the sibling render_template_to_pdf by indicating when to use each.

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?

Description explicitly says 'Use only when no starter fits' and 'Prefer render_template_to_pdf when a starter matches', providing clear when/when-not guidance with a named alternative.

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

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

Discloses payment model (USDC, $0.006 per render), header requirement, and error recovery (returns PaymentRequirement). Also explains data merging behavior. No contradiction with annotations (readOnlyHint=false). OpenWorldHint not explained, but overall transparent for a paid tool.

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?

Description is concise (~120 words) with well-structured sentences. Each sentence adds value: purpose, payment, error handling, data merging. No redundancy or fluff.

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 no output schema and minimal annotations, the description covers purpose, payment, parameter usage, and error scenario. Lacks explicit return structure beyond base64, but is otherwise complete for a paid template renderer.

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%, and description adds meaning beyond schema: explains merging for 'data', recommends calling get_starter for shape, gives example for 'pageOptions', and advises listing starters for 'template'. This enriches understanding significantly.

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 it renders a starter template to PDF and returns base64 bytes. It specifies the number of templates (45) and output format, but does not explicitly differentiate from sibling render_html_to_pdf, though purpose is clear.

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?

Provides detailed usage context: payment via x402, X-PAYMENT header handling, auto-retry for payment, and data merging behavior. Suggests calling get_starter and list_starters for guidance. Lacks explicit when-not-to-use guidance but context is strong.

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