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

Annotations already declare readOnly/idempotent/non-destructive/no-open-world, and the description adds real behavioral facts beyond them: count bounds 1–5000, refusal when neither step nor total is supplied, and the return value ('a list of seconds, one per item'). 'Free, read-only, no design needed' partially restates the annotations, which keeps this from a 5.

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?

Front-loaded with the core computation, then validation, then routing to the sibling – a sensible order with no filler sentences. The single dense sentence packs many clauses, making it slightly harder to scan than an ideal multi-sentence split.

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 no output schema, the description still names the return value (`times`, seconds per item) and covers the key failure mode and numeric bound. An agent can call this correctly without inspecting anything else.

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 coverage is high (83%), so the baseline is 3, but the description adds genuine semantics the schema only hints at: step and total are mutually exclusive ('give one of the two'), and the default/effect of ease on how gaps 'shrink or grow'. It does not detail 'in_out' behavior beyond naming it.

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 ('Compute start times for N items that cascade in') plus the mechanism (step or total, ease, start). It is immediately distinguishable from the sibling 'animate', which it names as the consumer of its output.

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?

Gives the use case ('time a list, grid or word-by-word entrance'), the downstream step ('pass the times to animate'), and an explicit when-not with the alternative named ('for a cascade over one layer's children, animate's own stagger is simpler'). It also states the selection rule between step and total ('give one of the two').

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