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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds genuinely new context beyond them: the default range is the last 7 days and results carry ids, which an agent needs to reason about output and defaults.

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 the subject and default window front-loaded and qualifiers following. It wastes no words, though it could be marginally clearer about the optional filtering.

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 read-only list tool with full annotations but no output schema, the definition is adequate but thin: it does not mention pagination, result caps, sort order, or the shape of returned session objects beyond "ids". The essentials for calling it are present, but not the full behavioral picture.

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?

With 50% schema coverage, from/to carry their format in the schema and area exposes its enum there, so the description's contribution is mainly mapping "project" to projectId. The projectId parameter itself remains undocumented in both the schema and the description, leaving the coverage gap only partially compensated.

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 (sessions), the scoping (a date range with a 7-day default), and the returned identifier fields. It is clearly distinguishable from the mutation siblings add_session, edit_session, and delete_session, though it never states an explicit verb like "list".

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?

It conveys the default window and the optional area/project filters, which implies a browsing use case. However, it offers no explicit when-to-use guidance versus alternatives such as summarize_day/summarize_week or find_gaps, and no exclusions or prerequisites.

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