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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description adds genuine behavioral context by enumerating the return envelope (latest value, unit, frequency, direction, aggregates, editorial prose, citations) and by calling out the exclusions. It says editorial prose is 'when available', which usefully warns of optional fields.

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 action and scope, then a dense single enumeration of returns, then the exclusion and slug examples. Three compact sentences with no filler, though the slug examples slightly repeat the schema.

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 carries the return-shape burden and does so: it lists every category of returned data, flags optional editorial prose, and points to where the full series lives. Only the unresolved sibling overlap (get_indicator_v2) keeps it from a 5.

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 the slug parameter is already fully documented including the 'use search_indicators first' hint and the 121-indicator count. The description's slug examples duplicate the schema rather than adding new semantics, so 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?

Names a specific verb ('Fetch') and resource ('American Default economic indicator by slug'), and enumerates exactly what the snapshot contains. However, it never distinguishes itself from the sibling 'get_indicator_v2', which an agent will see in the same list and may confuse it with.

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 scopes the tool to a 'compact snapshot' and states that raw historical series is NOT included, routing that need to the external JSON endpoint. That is a real when/when-not split, but the guidance is against an external URL rather than the sibling tools, leaving get_indicator_v2 and search_indicators unaddressed here.

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