sessions

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

With no annotations, the description carries the full burden, but it does contribute real behavioral information: 'most recent' discloses default ordering/recency scoping, and the field list effectively substitutes for the missing output schema. It does not state that the call is read-only, that results are truncated to a limited window, or what happens if there are no sessions, leaving meaningful gaps for an unannotated tool.

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?

A single tight sentence with a front-loaded resource and immediately enumerated payload, no filler or repetition. It loses a point only because the missing verb forces the agent to infer the action from context rather than reading it directly.

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 one-parameter list tool with no annotations and no output schema, the description usefully enumerates return fields and states recency ordering, which covers a lot of ground. It is still silent on the limit parameter, safety profile, and result-set boundaries, so it is adequate but not complete.

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?

The sole parameter (limit, default 10, max 100) has 0% schema description coverage and is never mentioned in the description. 'The most recent' hints at a recency-bounded result set but gives no hint that the caller can control the count or what the cap means, so the description does not compensate for the undocumented parameter.

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 (Codex sessions) and the exact fields returned (title, project, models, turns, tokens, dollar value), which lets an agent distinguish it from aggregate siblings like usage_summary or daily. It is a noun phrase without a verb ('list'/'retrieve'), so the operation is only implicit, but the intent is still unambiguous.

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?

There is no explicit when-to-use guidance and no mention of the five siblings (usage_summary, plan_limits, quota_forensics, daily, budget_status). The agent must infer from the word 'sessions' that this is the per-session drill-down rather than an aggregate view; nothing states that preference or any prerequisite.

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