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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely non-structured context: it operates without a workspace, is not metered, and reports 'history.available' to indicate whether per-client request history is included — details an agent could not get from annotations alone.

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?

It is front-loaded with the useful facts, but the middle sentence about a 'paste-ready card citing the MCP specification' and the SEP-2663 citation is presentation detail that does not help tool selection, and return-value description is partly redundant given an output schema exists. Trimming that would sharpen it.

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 an output schema present and zero parameters, the description need not document return shape, and the annotations cover the safety profile. What it adds — no workspace, no metering, history flag — is sufficient for an agent to call it correctly; only the missing sibling routing keeps it below 5.

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?

Zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly spends no space on arguments and instead frames the call as argument-free introspection.

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?

States a specific verb and resource — it reports what the server observes about the current request — and enumerates the exact fields surfaced (client name/version, User-Agent, protocol revision, Tasks-extension advertisement, auth shape, transport). That is clearly distinct from diagnostic siblings like service_status (server health) or guide_tasks (documentation), so an agent can pick it without opening the schema.

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?

The diagnostic intent is implied by 'what the server observes on this request' and the closing 'Read-only, no workspace, and not metered' tells the agent it is safe and cheap to call, but there is no explicit when-to-use framing and no named alternative (e.g., versus service_status) for related questions. Usage must be inferred.

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