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

Annotations only declare readOnly/openWorld/non-destructive; the description goes far beyond by disclosing the exact GA4 filter (landingPage + sessionSource google AND sessionMedium organic), why the channel group is not used, that ga4_conversions can exceed ga4_sessions, and that gsc_clicks will not equal ga4_sessions for stated reasons. These are interpretation-critical behaviors no annotation could carry.

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?

It is long, but for a two-source join most paragraphs earn their place, and the summary sentence is front-loaded before the scoping and caveat sections. Minor deductions for a garbled trailing clause ("one GA4 has no data for gets 0") and some restatement of the GA4-vs-GSC mismatch point across paragraphs.

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 complex cross-source join with four parameters, it covers the scope definition, join key and normalization rules, URL merging behavior, host separation, time zone mismatch and null handling. An output schema exists, yet the description still clarifies key row fields like ga4_scope and gsc_urls, leaving nothing an agent needs unresolved.

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 100%, so the baseline is 3, but the description adds real meaning: `limit` applies to top pages ranked by Search Console clicks, and both sides use the same date window (including the Search Console lag). It does not discuss site_url/property_id alignment beyond what the schema says.

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 opening line states a specific verb and resource pair — Google Search clicks per page joined to GA4 sessions, key events and revenue — and immediately frames it as a per-page join. This is distinguishable from siblings like ga4_top_pages or get_search_by_page_query because it explicitly combines both data sources rather than reporting one.

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?

It gives concrete example questions the tool answers ("which pages bring search clicks AND convert?", "which top-ranking pages get zero conversions?") and explains it takes top pages by Search Console clicks. It never explicitly names an alternative sibling or a when-not-to-use condition, so it stops short of a 5.

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