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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description still adds real value beyond them by stating 'Takes no arguments' and disclosing the return shape `{handle, root}` with the root's format — useful since no output schema exists. It stops short of noting edge cases such as an unset handle yielding a null root.

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 payload description, then the exclusion, then the arity — a sensible order with no filler. Minor friction comes from the reStructuredText-style backticks and the line-broken parenthetical, which add noise without adding 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?

For a zero-argument identity tool with no output schema, the description supplies the essentials: what is returned, its format, and the arity. It could be slightly more complete by stating what happens before an owner/handle is established and whether the root is always populated.

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?

With zero parameters the baseline is 4, and the description reinforces this by explicitly saying 'Takes no arguments', removing any doubt the agent might have from an empty properties object. There is no additional parameter meaning to add.

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 names the exact resource returned ('the owner's handle and root') and even spells out the root's format (`loci://<handle>/`), so an agent knows precisely what it gets. It also actively distinguishes itself from `list_nodes`, `search`, and `hydrate`, which an agent could otherwise confuse with a directory/identity lookup.

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 'Not for listing or reading nodes' line names three specific sibling alternatives and the condition that routes to them, which is strong negative guidance. Positive guidance is only implied ('what a full address is built from'), so an agent must infer the trigger case rather than being told 'call this when you need to construct a loci:// address'.

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