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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious behavior: the output includes a file that must be publicly hosted on the site, and the key must be wired in via INDEXNOW_KEY with a server restart. It stops short of saying whether an existing key is replaced or invalidated, and 'the server' is ambiguous (MCP host vs. the agent's own server).

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?

Two sentences, front-loaded with the action and its output, with zero padding. The second sentence is terse to the point of ambiguity about who restarts what, which costs a point.

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, non-destructive tool with no output schema and clear annotations, the description covers what is produced and the immediate next steps. The remaining gap is the lifecycle question (existing keys, key reuse) rather than anything needed to invoke it correctly.

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% with a single required 'host' parameter already documented with an example. The description adds no meaning about the host argument — e.g., whether it must match the domain used for later submissions — 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?

The description names a specific verb and resource — generate an IndexNow key — and states that it returns the file to host, which none of the reporting siblings do. The trailing instruction about setting INDEXNOW_KEY and restarting the server slightly blurs whether the tool performs those steps or merely advises them.

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?

Usage is only implied: an agent infers it should call this when it needs an IndexNow key. The description does supply a post-call workflow (host the file, set the env var, restart), but never says when not to call it or what to do if a key already exists.

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