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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description usefully enumerates the returned fields, but says nothing about behavior for an expired or unknown session_id, nor whether repeated calls consume resources.

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 no filler, front-loading the most useful information about what comes back. The fragment style omits a verb, which slightly weakens scannability but wastes no words.

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 read-only tool with full schema coverage and annotations carrying the safety profile, the definition is nearly sufficient, and it compensates for the absent output schema by naming the key returned values. Only error behavior for invalid or expired sessions is unaddressed.

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 coverage is 100% and the single session_id parameter is already documented in the schema as coming from start_session. The description adds no format, range, or validity detail beyond that, 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?

Names the resource (a session) and the specific data returned (status, remaining time, data used), which is far more informative than the title alone. It lacks an explicit verb and never references start_session/stop_session, so differentiation from siblings is implied only by the 'session_id returned by start_session' contract.

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?

No when-to-use guidance: it doesn't say to call this after start_session, whether it is meant for polling, or that stop_session is the terminating counterpart. The agent must infer all sequencing from sibling names.

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