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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds useful behavioral context beyond that: the response shape, the cost profile ('one call and a few kilobytes'), and its role as the cheapest discovery mechanism.

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 tightly written sentences with no filler. The description front-loads the core deliverable, then immediately provides decision-relevant guidance about cost, alternatives, and prerequisite usage.

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 read-only tool, the description is complete: it explains what is returned, the structure of that return, the cost, when to use it, and how it relates to sibling tools. No missing information an agent would need for correct invocation is apparent.

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 zero parameters and the schema coverage is 100%, so the description has no parameter burden to carry. It still indirectly clarifies that no configuration or arguments are expected, which is consistent with 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 states a specific verb and resource: returning the wiki tag hierarchy as a tree, with each node carrying path, name, description, and branch page count. It clearly differentiates itself from siblings like list_pages and search_wiki by positioning itself as an orientation and discovery tool.

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 says when to use this tool: to orient before searching and to find a valid tagPath before create_page. It also names an alternative to prefer against ('prefer it to listing pages to find out what exists'), giving clear comparative guidance.

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