List a domain's technology stack

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

Annotations already declare readOnlyHint=true, covering the safe read-only nature. The description adds valuable context beyond annotations by disclosing the cost ('Costs 1 credit') and the output structure (category and usage count). This provides useful operational insight not present in the structured 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?

The description is two sentences with no wasted words. It front-loads the core purpose, then adds the use case and cost information. Everything earns its place and is easy to parse.

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?

Even though there is no output schema, the description explains what is returned (technologies with category and usage count). It also covers the required input (domain), the optional limit is in the schema, and the cost is disclosed. For a simple read-only lookup tool, nothing critical is missing.

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 100% description coverage for both parameters (domain and limit), so the schema already documents them thoroughly. The description does not add any additional parameter-specific meaning beyond what the schema provides, which is the baseline for a high-coverage 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 tool's function: given a domain, list the technologies detected on it, including category and usage count. This distinguishes it from siblings like lookup_technology (which looks up a specific technology) and lookup_domains_technologies (plural, likely for multiple domains) by explicitly referencing 'a domain' and the technologies detected on it.

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 provides an explicit use case: 'Use this to answer what is this site built with?'. This tells the agent when to use it, but it does not mention alternatives or when not to use it, so it falls short of a 5.

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