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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description adds meaningful behavioral context: required OAuth scope 'journal:read', tenant ownership restriction, return order oldest→newest, and limit behavior. It also explains the intended use case in a cold session, which annotations cannot 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?

The description is four sentences and front-loaded with the core purpose. It packs in usage context, permissions, return behavior, and an example efficiently. The only slightly extra element is the cryptic 'CO 230-001' reference, but it does not detract significantly.

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 read-only replay tool with 2 well-documented parameters and no output schema, this description sufficiently covers when to call, prerequisites, ordering, and result shape. There is no significant missing context that would prevent correct invocation.

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% with descriptions for both tenant_id and limit, so the baseline is 3. The description adds value by emphasizing 'with only your tenant id', noting the return respects the limit, and providing a concrete invocation example. This goes slightly beyond the schema without being redundant.

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?

The description opens with 'Replay your agent journal oldest→newest', using a specific verb and resource along with ordering semantics. It also distinguishes itself from its sibling federation_journal_append by explicitly pairing with it as the write counterpart.

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?

It gives explicit when-to-use guidance: 'Call this at the start of a cold session — with only your tenant id — to reconstruct your intent and resume where you left off.' It also clarifies scope limitations (own tenants) and permission requirements, making the invocation context unambiguous.

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