List contacts

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so 'Read-only and takes no arguments' largely restates structured data and the empty schema. The description does add useful data semantics (carry-over behavior of earlier calls), but says nothing about ordering, completeness, or result limits for a potentially long list.

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 scope and followed by routing guidance; every clause carries information. The first sentence is long and packs five output fields, but none are filler.

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?

No output schema exists, so the description must carry the return-shape burden and it does, enumerating the per-contact fields. It omits ordering/pagination behavior, which matters for a full-list, argument-free tool, but otherwise an agent has what it needs to call 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?

Zero parameters, so baseline 4 applies; there is nothing to misinterpret. The 'takes no arguments' clause is redundant with the empty schema but harmless.

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 and resource ('List the people and businesses Smitline has called or been called by') and enumerates the fields returned (phone number, saved name/notes, call count, latest call, carry-over flag). It explicitly distinguishes itself from siblings list_calls and get_profile, so an agent can select it without opening schemas.

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?

Names two alternatives with the conditions that select them: list_calls with a contact for one contact's calls, and get_profile for people the user described. Combined with the stated scope ('people and businesses Smitline has called or been called by'), the routing decision is unambiguous.

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