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 genuine context beyond that: ordering of the notes, the journal's markdown with [[wiki links]] as the note format, and the two top-level return keys. It stops short of describing what fields `session` carries or behavior when no session exists on that date.

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 compact sentences, front-loaded with what is returned and in what order, then the format of the notes and the return keys. No filler; only the slightly listy 'Returns:' clause keeps it from being maximally tight.

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 simple two-parameter read with no output schema, the description covers the core content, ordering, note format, and return key names, which is enough to call it correctly. Minor gap: it does not say what happens if no session exists for that date, or what the `session` object holds.

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%, and the schema already states that the date is the session's address and that campaign accepts a slug or id. The description's 'One play date' adds emphasis but no new syntax, format, or edge-case meaning beyond the schema, 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?

The description names the resource concretely – one play date plus every shared note on it, in written order – and the 'Returns: `session` and `notes`' clause confirms it is a read of a single session. It implicitly contrasts with list_sessions (many) and update_session (write), though it never names those siblings explicitly.

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?

Usage is only implied: an agent can infer this is the single-session read that requires both campaign and date, versus list_sessions for enumeration. There is no explicit when-to-use or when-not-to-use guidance, and no sibling is named as an alternative.

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