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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful domain context: that these variables control period, year, scenario and version, which tells the agent why the read matters and what the returned values mean.

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, zero filler, with the core read operation front-loaded and the usage cue placed last. Every sentence contributes distinct information.

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 no output schema, the description correctly compensates by explaining what comes back: variable names, values and plan type scope. The only omission is whether results are paginated or filtered, which is minor for a small read-only lookup.

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%, with both appName and connection documented including their defaults, so the schema carries the parameter burden. The description adds no syntax or format detail for either parameter, making the baseline 3 appropriate.

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: 'Reads all substitution variables of an application,' and illustrates with concrete examples (CurrMonth, CurrYear) plus scope (values and plan type scope). It does not name the sibling update_substitution_variable outright, but the phrase 'before changing one' clearly separates it from the mutation counterpart.

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?

'Use it before changing one or when a form or rule depends on one' gives two concrete triggering conditions, which is stronger than implied usage. It stops short of naming the alternative tool or stating explicit exclusions, so it falls below a 5.

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