expiries_renew

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

Annotations already flag a non-read-only, non-destructive, non-idempotent write. The description adds real value beyond them: the old item is closed but preserved as history via renewedFrom, which fields are carried over, and exactly how expiresAt is defaulted per kind. It does not warn about duplicate renewals, though idempotentHint=false already signals 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?

Front-loads the action and its two-part effect, then the date defaulting, then the return shape. Dense but every clause carries information; only the long parenthetical duration list is a candidate for trimming.

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 write tool with no output schema, the description covers the side effects on both old and new records, the date-arithmetic fallback, and the returned keys ('item' and 'previous'). Nothing an agent needs in order to call it 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 coverage is 86%, so most parameters are documented already; the description still adds the derivation rule for expiresAt (kind-specific validity, counted from today if already expired) and confirms provider defaults to the old provider, which the schema states. That is meaningful semantics beyond the schema text.

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 ('Renew an expiry item') and immediately explains the compound behavior — creating the next item and closing the old one as history. That behavior distinguishes it from expiries_update and expiries_create without needing to name them explicitly.

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?

There is implied guidance about when the default validity kicks in ('Without expiresAt...'), but nothing says when to renew versus editing an item via expiries_update or creating a new one via expiries_create. The agent must infer the selection rule.

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