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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value annotations cannot: 'Public. No key.' discloses the auth model. Minor gap: it doesn't confirm the read is free of side effects or scoping limits, which the Easter-egg framing slightly implies.

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?

Very short and front-loaded: what it is, then WHEN, then access conditions, then an example. The leading 'Crown holder.' duplicates the title and earns little, but the total length is well under any wasteful threshold.

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 no parameters, rich annotations, and an output schema, the description only needs to explain the domain concept - and it does, defining the Dead Brands Crown as the Easter-egg first-claimant award. An agent can call this correctly from the description alone; only a note about the response shape or the claim sibling would make it fully complete.

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 parameters, so the baseline is 4 and there is nothing to mis-document. The inline example 'arena_crown_holder {}' actively reinforces that the call takes an empty object, which is a small helpful confirmation beyond the 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?

States a specific resource and read intent: 'see who holds the Dead Brands Crown'. That is clear and distinguishable from the sibling arena_crown_claim (which claims rather than reads), though the description never names that sibling explicitly. The opening 'Crown holder.' merely echoes the title but is immediately superseded by the concrete WHEN clause.

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?

'WHEN: see who holds the Dead Brands Crown' gives an explicit triggering condition rather than leaving usage implied. 'Public. No key.' adds a precondition (no auth) that an agent needs before calling. It stops short of 5 because it never explicitly says 'use arena_crown_claim instead if you want to claim the crown'.

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