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

Annotations already establish readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely useful behavior beyond that: the result contains a `display` markdown field with images and a swapchan.com link, and the agent is told to surface it to the user. However, it never describes the shape of the chain list itself (names, chain identifiers), so agents must discover callable chain IDs empirically.

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?

The purpose is front-loaded in the first clause, which is good. But the mascot conceit ("chain-chan mascot", "Swap-chan says") plus the long parenthetical list of playbook workflow names consume space that could carry information about the returned chain data.

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 output schema, the description carries the burden of explaining return values and does so only partially: it mentions `display` markdown but not the fields an agent needs to pass to other tools (chain names/IDs). Because this is a foundational lookup tool that gates most other siblings, that gap matters more than it would elsewhere.

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 takes zero parameters, so there is nothing for the description to disambiguate beyond what the schema shows. Baseline of 4 applies for a parameterless tool.

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: "List the chains SwapChan routes on." That is clearly distinct from the sibling get_supported_tokens by resource type (chains vs tokens), though the description never names that sibling explicitly. The mascot flavor text adds noise but doesn't obscure the core purpose.

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?

"Pick your departure gate!" is a thematic nudge to call this before choosing a chain, not an explicit when-to-use rule. The pointer to swapchan_playbook with named workflows (find-money, best-swap, etc.) gives real routing context, but nothing says when NOT to use this or how it differs from get_supported_tokens.

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