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

Annotations already establish read-only, idempotent, non-destructive, closed-world, but the description goes well beyond them: exact-first then substring matching order, the fallback behavior on an unknown term (returns a sample of available terms), what a hit returns (context, section anchor, deep link), and tier availability. These are behavioral traits an agent cannot obtain from annotations.

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 primary action and scoped tightly; every sentence carries information. It is dense and clause-heavy, which slightly taxes first-pass readability, but no sentence is redundant.

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-value burden and does so: it lists hit fields, fallback output, and overview fields. For a one-param read tool with full annotations, nothing an agent needs to invoke it correctly is missing.

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 a single optional param, so the baseline is 3, but the description adds meaning beyond the schema by spelling out what omitting `term` actually yields (phase, activation criterion, corpus size, enquiry address) rather than the schema's terse 'programme overview'.

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?

Specific verb (look up) plus a named resource (WEO Contribution Architecture vocabulary) with concrete example terms and an enumeration of the resource's sub-domains (terms, credit classes, governance provisions). It also explicitly disambiguates from the sibling get_methodology, so an agent can distinguish the two without opening either schema.

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 explicit when-to-use ('resolve participation vocabulary'), an alternative with its boundary ('the Methodology Manual (`get_methodology`) governs what qualifies'), and a mode-switch instruction ('Omit `term` for programme status'). Nothing about tool selection is left to inference.

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