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

Annotations already declare readOnly/idempotent/openWorld=false, so safety is covered; the description adds real value by spelling out what the output contains (ranked poems with read counts and last-read dates, breadth-vs-depth judgement). It doesn't explain that half_life_days tunes the recency weighting, which is the one behavioral knob a caller might misjudge.

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 verb and output inventory, then a distinct trigger sentence and a compact JSON example — every element earns its place. The first sentence runs long with semicolons, but no content is padding.

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 a rich output schema and full annotation coverage, the description need not explain return values or safety, and it appropriately focuses on scope and triggers. The only gap is that the recency-weighting parameter, which shapes the ranking it promises, is left to the schema alone.

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 (limit, half_life_days) are already fully documented and the baseline is 3. The description contributes only a small example ({"limit": 10}) and never clarifies half_life_days' effect on ranking, so it adds no meaning 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?

Uses a specific verb and resource ('Summarizes the reader's poetry reading in ReadingRate') and enumerates the concrete outputs: poems ranked by frequency and recency, heart-known line counts, and breadth-vs-depth. It's clearly differentiated in substance from generic siblings like get_reading_stats or get_top_books, though it never names those siblings explicitly to make the boundary unmistakable.

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?

The 'Use when the reader asks...' sentence gives three concrete, quotable trigger scenarios (which poems they return to, how much poetry they read, how many lines they know by heart). It stops short of stating when NOT to use it or naming alternatives such as get_reading_stats for prose or general reading.

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