explain_move

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

With no annotations, the description carries the full burden and does well: it discloses the authentication split (keyless FX vs EVDS_API_KEY), hard window limits per frequency (daily <=62 days, weekly <=1 year, monthly <=5 years), and an explicit non-goal (causation). Return format is left to the output schema, which exists, so that gap is acceptable.

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-loads the core action and its outputs in the first clause, then adds the evidence sources, the scope exclusion, and the access/limit constraints. It is dense but every sentence earns its place; only the long enumerations make it slightly heavy to scan.

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 six-parameter evidence-assembly tool with an output schema, the description covers what is computed, which evidence is gathered, authentication requirements, and window limits. An agent can call it correctly; the only omissions are the max_evidence knob and any sibling routing guidance.

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 83%, so the schema already documents start, end, series_code, keywords, and language. The description largely restates the series_code formats and evidence concept rather than adding new meaning, and it says nothing about max_evidence, the one parameter the schema also leaves bare. Baseline 3 applies when the schema does the heavy lifting.

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: 'Summarise how a series or exchange rate moved in a window' plus the evidence-assembly function, enumerating concrete outputs (first/last, change, min/max, largest moves). It is clearly distinguishable in spirit from siblings like get_series or compare_periods, but it never names an alternative, so the differentiation is implicit rather than explicit.

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?

Gives a clear scope boundary ('It assembles evidence; it does NOT establish causes') and practical preconditions (keyless FX codes with their window caps; EVDS codes require EVDS_API_KEY). It stops short of naming a sibling as the alternative when the agent wants a plain comparison or raw data, which keeps it below a 5.

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