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

Annotations already declare readOnlyHint and idempotentHint, so the safe-read profile is covered by structured data. The description adds one useful behavioral detail ('when the entry has them', i.e. optional fields may be absent) and implies the detail is public, but discloses nothing about error behavior for a bad entry_id or rate limits.

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 tight sentences, with the core fetch behavior and its distinguishing payload front-loaded before the routing sentence. No filler or repetition.

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?

With an output schema present and annotations covering safety, the description needs only purpose and routing, both of which it supplies. It stops short of covering failure modes (invalid/expired entry_id) or pagination, which is a minor gap given the otherwise complete structured metadata.

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 both parameters (entry_id provenance, lang enum plus default) are already fully documented in the schema. The description's restatement of entry_id/public_id adds no syntax or format detail beyond it, 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?

States a specific verb (fetches) and resource (full public detail for one directory entry) and names the identifier used (entry_id/public_id). It also enumerates the payload (phone numbers, opening hours, links), so the agent knows exactly what this returns versus the sibling search/browse tools.

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?

Explicitly routes usage: 'Use get_directory_entry for phone numbers and opening hours; use search_swiss_directory or browse_business_category to find an entry_id first.' This tells the agent both the selecting condition and the required prerequisite step, with the alternatives named.

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