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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description adds owner-scoping behavior ('ids you don't own answer Session not found'), auth requirements (Bearer token), plan restrictions (Pro/Teams), return shapes for both modes, and events for team sessions. This is substantive behavioral context beyond the annotations, with no contradictions.

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 dense but well-structured: it front-loads the purpose with 'Pro/Teams — list or inspect', then uses two numbered modes, field lists, cross-references, and auth/plan requirements. Every sentence contributes to understanding, with no filler except a harmless redundant 'Read-only' phrase.

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?

The description covers modes, returned fields, run timeline details, linking to related tools (validation_history, session_event, validate tools), where sessions are created, authentication, and plan requirements. With an output schema present, it does not need to enumerate return values further; it is complete for a list/inspect tool of this complexity.

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 input schema already provides 100% coverage with a detailed description of session_id, including the owner-scoping and 'Session not found' behavior. The tool description repeats this almost verbatim, so it adds no meaningful semantic value beyond the schema. Baseline 3 is appropriate given high schema coverage.

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?

Description explicitly states 'list or inspect the authenticated user's Governed Sessions' with a specific verb and resource, and distinguishes from siblings by defining sessions as durable containers grouping validation runs across lenses (architect.validate, design.validate, spec.validate). It clearly separates itself from me.validation_history, which is referenced for full run results.

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?

Two modes are clearly described: no arguments lists all sessions, while session_id=<id> inspects a specific session with its timeline. It explicitly directs users to me.validation_history for full run results and to the validate tools for attaching new runs, and notes sessions are created/managed in the web app. This provides clear when-to-use and alternative context.

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