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

Annotations already establish read-only and idempotent behavior. The description adds useful context beyond those annotations: each subscribed MCP sends its own digest, so multiple subscriptions produce multiple digests, and nothing is sent when this tool is used. This clarifies both semantics and side-effect-free behavior.

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?

The description is compact and well-structured. It front-loads the core question, then adds the per-MCP digest behavior in a second sentence. Every sentence adds value and nothing redundantly repeats the schema or annotations.

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-parameter, read-only tool with an output schema, the description covers the query target, the channel dimension, and the fact that nothing is sent. It does not enumerate the possible channels or explicitly identify the person, but these are reasonably left to the output schema and system context.

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%, and the schema already explains that mcp can be a name or id, matching is case-insensitive, and list_mcps can be used for disambiguation. The tool description adds no parameter-specific meaning beyond what the schema provides, so the baseline of 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?

The description clearly identifies the resource (one MCP) and the query intent: whether the person is subscribed to the weekly digest and through which channels. It does not use an explicit verb like 'retrieves' or 'returns', but the title and the read-only query phrasing make the purpose clear enough.

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 'Whether...' phrasing implies this tool is for checking subscription state, and 'Nothing sends yet' signals it is a safe read. However, the description does not explicitly name the obvious alternative set_digest or state when to use one versus the other.

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