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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered without the description. The description adds only the scoping context (overall vs. one contact) and says nothing about ordering, pagination, or result volume beyond what the structured fields carry.

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?

A single short sentence with no filler, and the primary trigger (user wants to see logged phone calls) is front-loaded. It could be tighter by dropping the trailing qualifier, but it is appropriately sized.

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 simple optional-parameter list tool with an output schema and full annotation coverage, the description is nearly sufficient. The remaining gap is ordering/recency semantics for a call log, which a user asking to "see calls" would likely care about, but nothing required to call the tool correctly is missing.

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% and both parameters (limit, contact_id) are documented there, so the baseline of 3 applies. The phrase "with one contact" loosely maps to contact_id but adds no syntax, format, or filtering detail beyond the schema.

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 (see) and resource (logged phone calls) and clarifies the two scopes: all calls or calls for one contact. It is readily distinguishable from write siblings like calls.create or calls.delete, though it never contrasts itself with calls.get or contacts.timeline.list.

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?

"When the user wants to see logged phone calls" provides an intent trigger, and "either overall or with one contact" implies the two filter modes. However, it gives no exclusions or alternatives, so an agent cannot tell from the text when calls.get or contacts.timeline.list would be the better pick.

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