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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, but the description adds the crucial reason: 'Recording this delivery is what makes the next recall's change exact', explaining the write side effect that justifies the non-read-only/non-idempotent flags. It also adds the auth requirement ('Needs your key') and names the return payload (sb.watch-reading.v1), context beyond the bare annotations.

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 compact but front-loads a sentence about free configuration/paid saving that is product positioning rather than invocation guidance, diluting the most useful content. The genuinely useful behavioral and delivery-recording details come after that detour.

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 usefully states the return content (current reading plus changes since last delivery, sb.watch-reading.v1) and the auth need, which is adequate for a 2-parameter tool. Minor gaps remain around the delete/retire and filtering alternatives, but the essentials for calling it correctly are present.

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%, so both parameters (watchId, expand) are already documented in the schema and the description adds no syntax or format detail for them. This matches the baseline 3 where the schema does the heavy lifting.

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 core clause 'Recall a saved Watch: its reading now ... and what changed since the last time it was delivered' gives a specific verb and resource, and distinguishes it from save_watch/unfurl_watch by naming the saved-watch recall action. The purpose is slightly obscured by the leading sentence about free configuration/unfurling and paid saving, which describes the Watch product generally rather than this tool.

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 no explicit when-to-use or when-not guidance relative to siblings like list_saved_watches or get_watch_feed. The only usable context is the implied 'needs your key' prerequisite and the REST endpoint equivalence, leaving the agent to infer when this is the right call.

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