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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds only scoping (one site, identified by id), and its field enumeration largely restates what the output schema already provides. It says nothing about behavior on a missing/invalid id, which is the remaining useful gap.

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?

Three compact sentences: the core fetch and its payload first, then two disambiguation sentences. No filler, and the most important 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?

A one-parameter read tool with an output schema, full schema coverage, and four annotations needs little else; the description covers purpose, payload scope, and sibling routing. Nothing required to invoke it correctly 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?

Schema description coverage is 100% and the single siteId parameter is documented in-schema with an example source ("from list_sites"). The description's "by id" adds no format, constraint, or sourcing detail beyond that, so the baseline of 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?

Uses a specific verb ("Fetch") plus resource ("one hosted site by id") and enumerates the returned facets: project, address, template, status, suspension end, badge rule, live deploy, newest deploy. This distinguishes it cleanly from list_sites (plural listing) and update_site (mutation) in the sibling set.

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 routes two adjacent needs to alternatives: "For the deploy history, use list_site_deploys" and "For page views, use get_site_usage." An agent choosing between the single-fetch tool and its list siblings has a direct rule rather than an inference.

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