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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds genuinely useful context beyond that: 'Factual data only — MarketPing publishes no buy/sell recommendations, no price targets and no IPO grey-market premium,' which discloses content boundaries an agent would otherwise learn only after calling the tool.

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?

Three short sentences with zero waste: purpose/content in sentence one, usage timing in sentence two, content boundary in sentence three. The core purpose is front-loaded and every sentence earns its place.

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 zero-required-parameter catalog tool, the description conveys what is returned ('labels, units and groups'), when to call it, and the factual-only scope. No output schema exists, so return format is lightly specified, but result size and pagination are minor concerns for a metadata catalog and the annotations cover safety.

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%, and both parameters (group, featured_only) are well-documented in the schema itself. The description's mention of 'groups' as catalog content loosely ties to the group parameter but adds no operational detail beyond the schema, so the baseline 3 applies.

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 description states a specific purpose: enumerating the metrics available for filtering/sorting in run_screener, 'with labels, units and groups.' It explicitly names the sibling tool run_screener, making clear this is the catalog/reference tool while run_screener executes screens — no ambiguity about which sibling this is.

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?

'Call this before building a screen if you are unsure of a field name' gives explicit timing and the triggering condition for use. It stops short of naming when-not-to-use or listing alternative catalog tools, but the conditional is clear enough that an agent can decide correctly.

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