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

Annotations already declare readOnly/idempotent/non-destructive, yet the description still adds real behavior: newest-first ordering, the fact that hash-chain verification 'breaks where an entry was changed or removed', and that the call is free. It stops short of describing pagination/cursor behavior or what an entry looks like, so not a full 5.

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 dense sentences: the first front-loads scope and the enumeration, the second carries the sibling pointer and the verify semantics plus the cost note. No filler, no repetition of the title.

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?

For a 4-param, no-output-schema read tool, this covers scope, ordering, the security-relevant `verify` mode, cost, and the competing tool. Remaining gaps are the two undocumented filters (`since`, `limit`) and any hint about entry shape, but nothing blocking an agent from calling it 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 only 25% (only `action` is documented in-schema), so the description has to compensate. It does explain `verify` semantics well and effectively hints at `action` prefixes by listing event categories, but `limit` and `since` get no treatment at all — no guidance on time-window format or default/max behavior.

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?

Names the resource precisely (the account's admin and security actions) and enumerates the concrete event classes captured: key creation/revocation, limits and auto-reload, owner sign-ins, connectors, exports, vault reads/writes, credential changes, deletions. This is specific enough that an agent can distinguish it from account_events and account_list_calls without opening any 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?

Explicitly routes the alternative: 'Ordinary work is in the call log (account_list_calls)', telling the agent exactly when to pick the sibling instead. It also gives a conditional usage rule for a parameter ('verify: true also checks the hash chain'), which is when-to-use guidance at the argument level.

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