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

readOnlyHint already tells the agent this is a safe read, so the bar is lower. The description usefully enumerates what comes back (id, ready, pageCount, defaultFor) and distinguishes pattern vs block ids, but adds nothing about pagination, ordering, or volume limits.

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?

Front-loaded with the purpose, followed by field semantics and a routing hint. The long field enumeration is somewhat redundant with the published output schema, which is a minor cost, but every clause still carries information.

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 no-param, read-only list tool is well covered: purpose, output fields, and the create-vs-update routing decision are all present. Since an output schema exists, the field list is a bonus rather than a requirement, and 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?

Zero input parameters, so the baseline is 4 by rule. The description instead documents the shape of the returned entities, which usefully disambiguates headerPatternId/footerPatternId from headerBlockId/footerBlockId.

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?

Specific verb+resource ('List the site templates') with a clarifying gloss ('header+footer frames') that implicitly separates it from fabrement-list-template-pages. It does not name or contrast any sibling explicitly, so differentiation is inferred rather than stated.

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?

Gives a clear when-to-use trigger ('Call FIRST when the user may mean an EXISTING template') and a downstream action ('update it by id instead of creating a duplicate'). No exclusions or alternatives are offered, e.g. when to reach for get-template or list-template-pages instead.

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