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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered. The description adds two useful behavioral facts beyond that: the numbers are "live" (not a stale snapshot) and results carry "with dates" for recency. It says nothing about caching, refresh cadence, or auth needs, so it is additive but modest.

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?

One front-loaded sentence names the payload before any filler, and the no-input note is short. The "Example: {}" clause is nearly redundant with "Takes no input" but is harmless for a zero-argument tool and costs little space.

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?

An output schema exists, so the description need not explain return shapes, yet it still previews the main fields an agent will get back. What remains unstated is whether the totals are global over the whole directory or otherwise scoped, and how "live" is measured — minor gaps for a no-parameter read tool.

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 takes zero parameters, which is the baseline-4 case. "Takes no input. Example: {}" reinforces that no arguments are expected, eliminating any guesswork about whether a scope or date filter can be supplied.

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?

"Live directory totals" states a specific resource and output type, and the enumeration of what is counted (listings by kind, consultation fee range/median, delivering pharmacies) makes clear this is an aggregate-stats tool rather than an entity lookup. It does not name any sibling (e.g. search_directory or the find_* tools) to explicitly contrast with, so it stops short of a 5.

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?

"Takes no input" plus the aggregate framing implies this is the tool to call for summary statistics instead of individual records, but the description never states when to prefer it over search_directory or the find_* siblings, nor any exclusions. Usage is inferable from the content rather than stated.

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