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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes beyond them with two genuinely additive facts: the tool never raises a protocol error but returns {"error": ...}, and only the first 2000 rows are profiled. It also states retry-safety after correction, which is behavioral guidance no annotation field conveys.

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?

Purpose is front-loaded in the first clause and the FREE marker is immediate. The inline example output is somewhat verbose and partially redundant with the output schema, but every sentence (usage, exclusions, error contract, retry safety) carries information an agent needs.

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 2-parameter read-only profiling tool with an output schema and full annotations, the description covers purpose, alternatives, error semantics, truncation limit, and retry safety. An agent could call and recover from failures correctly using this text 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 coverage is 100%, so the baseline is 3; the description earns an extra point by showing a concrete input string ({"csv_text": "name,age\nAda,36\nLin,29"}) that makes the 'paste raw CSV with header row' convention unambiguous. The delimiter error sample ('delimiter must be a single character') reinforces the one-character constraint, though most of this is restating 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 a specific verb and resource: 'Profile pasted CSV data column by column with data-quality flags', then enumerates exactly what it reports (type, null rate, unique count, min/mean/max, top values). The sibling-exclusion sentence ('Not for testing a hypothesis... not for time-ordered trends') lets an agent disambiguate from ab_test, correlation, growth_rates and forecast_trend without reading their schemas.

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?

Explicitly prescribes the use case ('Use as the first look at unfamiliar tabular data') and names four sibling alternatives with the condition that excludes each. Both when-to-use and when-not-to-use are present, which is the top of the scale.

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