session_detail

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

No annotations are provided, so the description carries the burden; 'Read' signals a non-mutating operation, and it discloses that the timeline is returned in order and spans three entry types, which is real behavioral content. It does not mention permissions, rate limits, or how truncation behaves when limit/frames are exhausted, so it falls short of full disclosure.

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: the first front-loads what is returned, the second front-loads when to reach for it. No filler, no repetition of schema fields.

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 and no annotations, the description must stand alone; it usefully describes the returned timeline composition (messages, replies, tool calls) and ordering, covering most of what an agent needs. It stops short of describing response shape or truncation semantics, which is the main remaining gap.

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 all three parameters (limit, frames, session_id) are documented in the schema, including the prefix-matching behavior of session_id. The description adds no parameter-level detail beyond what the schema already supplies, 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 (Read) plus a precisely scoped resource (the recent activity timeline of ONE DSH session) and enumerates what the timeline contains: human messages, agent replies, tool calls. This distinguishes it from siblings like peers (list) and overlaps without needing to open 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 sequences usage: 'Use it after `peers` when another session's work matters to yours,' naming the sibling that precedes it and the triggering condition. It lacks an explicit when-not clause (e.g., what to use for a broad multi-session view), but the routing intent is clear.

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