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

Annotations already declare the safe read profile (readOnly, idempotent, non-destructive), and the description adds genuine behavior: empty list when no linkGroup exists, 404 for unknown/non-editable characters, and the permission scoping. It does not address pagination or ordering, but for a sibling list that is minor.

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 dense sentences that are front-loaded with purpose, then workflow, then edge cases. Slightly long but each clause (linkGroup definition, sibling-tool routing, error states) earns its place.

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?

With an output schema present, return fields needn't be spelled out, yet the description still names the summary-row keys and the follow-up call. Permission model, empty-result, and 404 cases are all covered, leaving nothing an agent needs to call this correctly.

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% and the single `id` parameter is already documented as the Mongo `_id` with the same ownership/admin qualifier the description repeats. The description adds no syntax or format detail beyond the schema, so baseline 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?

Specific verb (List) plus a precisely scoped resource (linked sibling sheets — every OTHER sheet in a character's linkGroup), and it distinguishes itself from vault_get_character (summary vs. full sheet) and vault_spawn_linked_character (which creates the links). An agent can identify this tool without inspecting siblings.

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?

Provides clear routing: use this to find sibling sheets, then call vault_get_character for the full sheet, and states the edit-permission context (own character or admin with Admin Mode). It lacks an explicit 'do not use this for X' exclusion against vault_get_character/vault_search_characters, but the workflow guidance is strong.

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