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

With no annotations, the description carries the full burden. It discloses that disputed dates carry both positions 'never one verdict', and it explains the different behaviors for passing an id vs. no id. This goes beyond the schema and adds useful behavioral context, though it doesn't mention output format or potential limitations.

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?

The description is three sentences and covers scope, disputed-date policy, and usage. The opening 'Timeline —' is slightly redundant with the tool name, but it sets a clear header for the scope. Each sentence adds distinct value, and the text is front-loaded with the most important information.

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 read tool with one optional parameter and no output schema, the description provides enough to understand the tool's function and major behavior. It explains what you get when passing id vs. not, and highlights the disputed-date stance. It stops short of fully detailing the event data structure, but that is not critical for selection and invocation.

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 schema only provides an optional 'id' string with maxLength, so description coverage is 0%. The description compensates fully by explaining that the id selects a single event, and that omitting it lists all events grouped by era and period. This gives meaning to the otherwise opaque parameter.

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 clearly states this is a timeline covering Old Testament, New Testament, and Church History, and distinguishes it from sibling tools by specifying the 'one spine from creation to today' scope and the handling of disputed dates. It also gives concrete usage behavior: pass id for one event, else list all grouped by era and period.

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 usage: use it for chronological events, with or without an id. However, it does not explicitly mention when not to use it or name alternative tools, so the guidance is inferred rather than explicit.

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