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

Annotations already declare readOnly and idempotent; the description adds conditional portfolio behavior for keyed callers with saved sites, the cache-and-pass-back generated_at workflow, and the default 24h window — all beyond the structured annotations. No contradictions.

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?

Long but every phrase earns its place: definition, return categories, conditional behavior, parameter syntax, use cases, example. Front-loaded with 'Incremental sync' and organized with dashes and line breaks.

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?

Covers what it returns, conditional portfolio block, parameter usage, caching recommendation, and example call; an output schema exists for field-level detail. There is no meaningful gap for agent 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?

Schema already covers both parameters (100% coverage), so baseline is 3; description adds the workflow of caching generated_at and passing it back as since, and gives a concrete example (since=7d), which is extra semantic value beyond the schema.

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 'Incremental sync — what changed in DC Hub since a timestamp' with a specific verb and resource, and enumerates the return categories. This clearly distinguishes it from siblings like get_news or fetch by its delta scope.

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 concrete trigger use cases ('what changed since I last looked', 'anything new this week I should know about') and explains it replaces re-fetching everything. It does not explicitly name sibling alternatives or exclusion conditions, so it stops short of full routing guidance.

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