unphurl-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively explains key behavioral traits: this is a read-only operation (implied by 'Check'), it discloses credit consumption rules (credits consumed only for unknown domains in full analysis, known/cached domains are free), and it describes what happens when credits run out (credits_remaining=0 still allows free checks for known/cached domains). However, it doesn't mention rate limits, authentication needs, or error conditions.

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 efficiently structured in three paragraphs: first states the purpose and what information is returned, second explains credit consumption rules, third provides usage guidance for low credits. Every sentence adds essential context without redundancy, and 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?

For a zero-parameter tool with no annotations and no output schema, the description provides excellent context about what the tool does, when to use it, and important behavioral details about credit consumption. However, it doesn't describe the return format (though this is somewhat implied by listing the data points) or potential error conditions, leaving minor gaps.

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 tool has 0 parameters with 100% schema description coverage, so the baseline is 4. The description appropriately doesn't discuss parameters since none exist, and instead focuses on the tool's purpose and usage context, which adds value beyond the empty 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 the specific action ('Check your pipeline check credit balance') and resource ('credit balance'), distinguishing it from siblings like 'purchase' (for buying credits) or 'get_pricing' (for pricing information). It provides concrete details about what information is shown (credits remaining, total purchased, total used, lifetime free lookups count).

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?

The description explicitly states when to use this tool ('Check your pipeline check credit balance') and when to use an alternative ('To check unknown domains, purchase more credits using the "purchase" tool'). It also provides context about free vs paid usage (known/cached domains are free, unknown domains consume credits), helping the agent decide when to check balance versus when to purchase.

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