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

Discloses a genuinely non-obvious behavior: lazy-creation on first read, which explains why readOnlyHint is false for a 'get' tool. It also spells out the authorization model, including the 403 condition for the GM-only dm-notes, none of which the annotations convey.

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 sentences, none wasted: purpose first, behavior second, permissions third. Dense but front-loaded and easy to scan.

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, the definition need not explain return values; it fully covers the two things an agent needs beyond structured data – the lazy-create side effect and the access control rules.

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%, so baseline is 3, but the description adds access semantics that map directly to documentType ('the DM-side note (dm-notes) is the GM's alone'). The characterId caveat lives only in the schema, so the description does not improve on both parameters.

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?

States a specific verb and resource ('Fetch the DM-side or player-side note attached to a play character') and immediately distinguishes the two document variants. An agent can tell it apart from play_update_character_note without opening the schema.

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 clear context on when this works and who can call it, plus the useful fact that it always returns a note. It does not explicitly route to play_update_character_note for writes, which is the obvious sibling, so it falls short of full when/when-not guidance.

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