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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context about the time window ('today') and ranking criterion ('percentage price decline'), which goes beyond the annotations. However, it does not describe return format, pagination, or other behavioral traits, so it offers moderate added value.

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?

The description is two sentences, front-loaded with the core purpose, and contains no filler. Every word contributes to understanding what the tool does and when to use it.

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?

Given the tool's simplicity (one optional parameter, no output schema), the description fully covers the tool's purpose, usage context, and ranking behavior. It is complete for a filtered-list tool with good annotations.

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?

The input schema has 100% description coverage for the single 'limit' parameter, which is documented with type and default. Since the schema fully explains the parameter, the description's lack of parameter detail is acceptable. Baseline of 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 clearly states the tool's function: 'Get the top losing stocks on the NGX today, ranked by percentage price decline.' It uses a specific verb ('Get'), specifies the resource (NGX stocks), and adds a distinguishing scope ('top losing', 'ranked by percentage price decline') that differentiates it from sibling tools like get_ngx_top_gainers and get_ngx_all_stocks.

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 description provides explicit usage guidance: 'Use this when the user asks which Nigerian stocks are down the most today.' This clearly identifies a triggering user request. However, it does not explicitly state when not to use it or name alternatives, so it falls short of a full 5.

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