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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real behavioral context beyond that: the 404-on-miss error contract and the `is_infrastructure` flag that distinguishes backend CDN/DNS/cloud infrastructure from a human-navigable site. Only the shapes of these are left implicit.

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?

Purpose is front-loaded and the three sentences are dense with useful detail rather than padding. The trailing 'Use web_techstack...' sentence sits oddly at the end and reads more like a cross-sell than a routing rule, slightly blunting the structure.

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?

An output schema exists, so return values need not be spelled out, yet the description still sketches the payload plus the 404 case and the infrastructure caveat. For a single-param read tool with full annotations and an output schema, this is close to complete; only the relationship to the sibling retrieval tools remains fuzzy.

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% with a single documented `domain` parameter including an example, so the schema carries the meaning. The description only restates 'by its domain' and adds no format, casing, or normalization guidance beyond what the schema provides — baseline 3 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?

States a specific verb and resource ('Returns one site by its domain') and pins it to the `techstack` dataset, then enumerates the returned payload (technology name/categories/confidence/version/evidence plus CMS/e-commerce/CDN/web-server/language rollups). An agent can distinguish it from datasets_techstack_search (search) and datasets_techstack_facets without opening a schema.

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?

It names an alternative ('Use web_techstack to retrieve tech stack') and states a boundary condition (404 when the domain is not indexed), but never explains when to prefer this dataset item over web_techstack or datasets_techstack_search. The routing sentence is helpful yet somewhat self-undermining since this tool's own job is to return tech stack for a domain.

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