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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds behavior beyond that: results are sorted, capped per call by limit, and paginated via a next_after cursor. It does not mention sort key or rate limits, but the pagination loop is the critical behavior an agent needs.

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?

Two tight sentences with zero waste; the enumeration scope is front-loaded and the pagination rule follows immediately. Every clause 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 no output schema, the description usefully explains the next_after return field that drives pagination, which is the main thing an agent must know. Minor gaps remain: it says results are 'sorted' without stating the sort key, and gives no hints on prefix semantics beyond the schema.

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 description coverage is 100%, so after, limit, prefix, instance_id, and passport_token are all documented in the schema itself. The description adds only marginal framing (limit is 'per call', after chains from next_after), so the 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?

States a specific verb (List) and resource (keys in your memory locker), which is clearly distinguishable from the sibling verbs locker_get, locker_put, and locker_delete. An agent can tell this enumerates keys rather than fetching values.

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 operational context: it tells the agent to call again with after = next_after while next_after is not null, which is a concrete usage instruction. It stops short of naming when-not-to-use or explicitly routing against sibling tools like locker_get.

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