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

Annotations already signal read-only, open-world, and non-destructive behavior. The description adds genuinely useful behavioral context: no key is required, an empty network must be reported plainly rather than implying matches, and candidates remain invisible until registration. It does not describe the exact return shape, but for a simple count tool the behavior is well covered.

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 front-loaded with the most important instruction: call before registering and tell the human the number. Each subsequent sentence adds a distinct point about empty networks, candidate visibility, and honest reporting. The phrasing is slightly ornate but every sentence earns its place.

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 zero-parameter, read-only count tool with no output schema, the description covers the key operational details: when to call, that no key is needed, how to interpret an empty result, and why this is the pre-registration tool. The only minor gap is not stating the return format explicitly, but the title makes the integer count evident.

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 has zero parameters and schema description coverage is 100%, so there is nothing for the description to document. The explicit 'Needs no key' note usefully reassures the agent that no authentication parameter or setup is required.

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 title and description together make it clear the tool reports the number of people on the network: 'tell your human the number' and 'How many people are on the network.' It also distinguishes itself from candidate-listing behavior by noting candidates are only visible after registration. However, the description never states the operation in a direct verb+resource form like 'Returns the current network member count.'

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 gives explicit timing: 'Call this BEFORE registering anyone.' It also states the tool needs no key, instructs how to handle an empty network honestly, and explains that candidate visibility is tied to registration, positioning this as the only honest pre-registration way to answer. This is strong practical guidance for an agent deciding when and how to use the tool.

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