session_stats

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

Annotations already declare readOnlyHint=true, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds only that the scope is 'this session' and that output is user-facing prose; it says nothing about what data is included or whether it reflects only this MCP server's calls. With annotations carrying the safety profile, this is thin added value.

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 short sentence with no padding, and the scope qualifier lands immediately. It is efficient but under-specified rather than over-long, so it loses a point only for lack of substance.

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?

With no output schema, the description carries the burden of explaining what the agent gets back, and it does not: no mention of which metrics (call counts, per-tool breakdown, timing) or of the response shape. For a zero-param read tool this is low-stakes, but it is still incomplete.

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 tool takes no parameters (schema is an empty object with additionalProperties false), so there is nothing for the description to disambiguate. Baseline 4 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?

The description identifies a resource — tool usage during this session — and the verb is an instruction to report it to the user. It is distinct from every sibling (all scraping/browser tools), but 'tool usage' is vague about what is actually returned (counts, durations, per-tool breakdown).

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 statement of when to call this versus anything else, no triggers, no exclusions. The only implied usage is 'when the user asks about session activity', which the agent must infer from the phrase 'during this session'.

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