Get active character

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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, so safety is well covered. The description adds useful behavioral context beyond annotations by noting the value is 'locally persisted' and that the active character may not be configured, implying a possible absence result. It does not detail the exact return shape when unset, but the conditional phrasing partially covers that.

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 sentence with no wasted words, front-loaded with the action and resource. It is appropriately sized for a zero-parameter getter.

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, zero-parameter, read-only getter with rich annotations, the description is mostly complete: it states what is returned and the configuration condition. The only minor gap is not explicitly describing the fallback behavior when no active character is configured, though 'if one is configured' strongly implies it.

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 are no parameter semantics to clarify. The description correctly focuses entirely on the return value rather than inputs.

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 uses a specific verb ('Return'), identifies the resource ('the locally persisted active character'), and adds a scope condition ('if one is configured'). It clearly distinguishes itself from mutating siblings like set_active_character and clear_active_character.

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 implies when to use the tool by defining it as the getter for the active character, but it does not explicitly state when to choose this over alternatives or mention related tools such as get_character_summary. The usage context is clear but not fully spelled out.

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