session_summary

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

With no annotations, the description carries the full burden and does well: it discloses ordering semantics (threads in order from the first prompt, records with outcomes first), scoping (files touched in that range), and the crucial data-freshness trait that results are historical records rather than live state. It stops short of covering result size, truncation, or cost of a call, so not a 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?

Three sentences, front-loaded with purpose, then routing, then the freshness caveat; the parentheticals all carry information rather than filler. Nothing could be removed without losing selection-critical detail.

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 read tool with no output schema, the description conveys the return shape well enough (header fields plus an ordered journey of threads and records) and flags the historical nature of the data. It leaves open the default selection behavior when no identifying parameter is given, and jargon like 'records'/'threads' is not defined, which is a modest 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%, so `last`, `repo`, `session_id` (including the ≥8-char prefix rule) and `recall_token` are already fully documented in structured fields. The description adds nothing about parameters — notably it never explains selection precedence when neither `last` nor `session_id` is supplied — so 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 and resource ('Get one coding session's header ... and its JOURNEY') and enumerates the returned fields (repo, branch, turns, models, files touched, threads, records). It explicitly names the sibling get_code_session and the condition that selects it, so an agent can route without opening either 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?

Gives a positive selection rule ('short story of a session — what it set out to do and what it found'), names the alternative for a different need ('use get_code_session when you need the actual turns, e.g. the exact words around a memory_search record'), and warns when not to rely on it ('dated records ... not the current state of a PR or issue; check that live').

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