Echo a connectivity probe

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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, and the description builds on this by adding behavioral details not in annotations: no network I/O, no quota side effects beyond the tool gate, and the exact return shape (message plus server name/version). This is exactly the kind of added context that helps the agent reason about side effects.

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?

Three sentences, no wasted words. Purpose, usage, exclusions, safety traits, and default behavior are all covered in a compact, front-loaded structure.

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 single-optional-parameter tool with rich annotations and an output schema, the description is fully sufficient. There is nothing an agent needs to know to call it correctly that is missing: behavior, output, side effects, default, and alternatives are all addressed.

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 description coverage is 100%, so the schema fully documents the message parameter, including its default value and behavior ('Payload echoed back unchanged'). The description repeats the default but adds no new parameter-specific meaning beyond what the schema already conveys.

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 clearly states a specific verb and resource: 'Return the provided message plus server name/version to confirm the MCP session is alive.' It also explicitly differentiates from sibling tools by positioning itself as a liveness probe rather than a discovery or persistence tool.

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 description explicitly says when to use it ('Use as a liveness probe') and when not to use it ('Do not use to discover tools (discover_capabilities) or to persist state'). It names an alternative and provides clear exclusion conditions.

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