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

With no annotations, the description carries the full load and does well: it discloses side effects (files written to out_dir, magic-byte verified), auth requirements (none), and a latency warning ('Large carousels can take a minute'). It does not state failure/timeout behavior, but covers the major behavioral traits an agent needs.

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 verb and resource, then adds return/manifest and constraint details in a single dense paragraph. Every clause is informative, though the parenthetical list of manifest contents is slightly heavy.

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?

No output schema exists, yet the description enumerates the return envelope (author, caption, media URLs, local files, errors, decode-slot provenance) and covers auth, latency, and disk effects. For a 3-parameter tool this is complete enough for correct invocation.

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 schema already documents url, out_dir, and download_media. The description reinforces accepted URL forms and out_dir behavior but adds little parameter meaning beyond the structured fields, matching the baseline 3.

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 (Harvest/download) plus resource (public Instagram post/carousel/reel), with scope made explicit ('public', 'given a post URL, share link or bare shortcode'). It clearly differentiates itself from siblings like lookup_post (metadata) and read_manifest (inspection) by describing end-to-end media download.

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 clear context for use ('given a post URL... downloads every exposed photo and video') and constraints ('public', 'No login, no API keys'). It does not explicitly name when to prefer a sibling such as lookup_post over this tool, so it stops short of full when/when-not guidance.

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

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

With no annotations, the description carries the full burden and does disclose the return format (JSON Schema draft-07) and the target version (post_manifest envelope, schema_version 1.0). It omits auth or size characteristics, but for a parameterless static-schema read this is solid disclosure.

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?

A single front-loaded sentence with zero waste: verb, resource, format, version, and purpose each appear once. Nothing is padding.

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 no-arg tool whose output IS the schema, the description adequately explains what comes back even without an output schema. It could note the response size or that it is static, but nothing essential is missing for correct invocation.

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 tool takes zero parameters, so the schema-to-description burden is nil; the baseline of 4 applies. Nothing in the description misrepresents the parameter surface.

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 states a specific verb and resource: it returns the JSON Schema (draft-07) for the post_manifest envelope. It is clearly distinct from read_manifest (which returns data rather than the schema), though it does not explicitly name siblings to route the agent.

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?

It gives clear usage context — 'use it to validate or explore the output contract' — which tells the agent why and when to call it. There are no explicit exclusions or named alternatives, but the intent is unambiguous.

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

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 metadata-only behavior, that no media files are written, that it applies to public posts, and that it shares the decode pipeline with extract_post. It omits failure modes (private/deleted posts) and any rate-limit or auth expectations, which keeps it from a 5.

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?

Two sentences, zero filler: the core behavior leads, the routing guidance follows. The dense em-dash clause is still readable and every phrase (field list, --no-download, public) earns its place.

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 and no annotations, the description compensates by enumerating returned entities (author, caption, timestamps, media URLs, carousel shape) and the file-writing side effect. Remaining gap is error/edge-case behavior for non-public posts, which is minor but real.

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% — url format and out_dir/manifest semantics are already documented in the schema, including share links and bare shortcodes. The description reinforces the manifest output but adds no format or constraint detail beyond the structured fields.

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 names a specific verb and resource ('metadata-only lookup of a public Instagram post') and explicitly positions itself against the sibling extract_post ('same decode pipeline as extract_post but with --no-download'). It even enumerates what metadata is returned, so an agent can distinguish it from extract_post 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?

It gives a clear selection condition ('Use this when you only need to read the post') and implicitly routes download needs to extract_post via the --no-download contrast. It stops short of an explicit when-not or a named alternative invocation, but the context is unambiguous.

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

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

With no annotations, the description carries the burden and does disclose concrete behavior: it refuses any file not named post_manifest.json and returns the full envelope. It does not state permission requirements or failure modes beyond the name check, so it isn't fully transparent.

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?

Two short sentences, nothing wasted; the purpose and the hard constraint are both front-loaded and easy 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 one-parameter read tool with no output schema, the description covers purpose, provenance, and the filename restriction. The phrase 'return the full envelope' is only loosely informative about the return value, which is acceptable but not maximally clear.

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 single parameter is already fully documented in the schema ('absolute path to a post_manifest.json'), so any description of it duplicates structured data. The 'refuses any file not named post_manifest.json' line adds a validation nuance, but the schema coverage is 100%, which sets the baseline at 3.

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 (read) and resource (an existing post_manifest.json), and ties provenance to prior tooling ('produced by a previous extract/lookup'), which cleanly separates it from extract_post and lookup_post.

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?

Clearly frames the use case as re-reading output from a prior extract/lookup, plus a hard constraint (refuses files not named post_manifest.json). It lacks an explicit 'when not to use' or a named alternative, so it stops short of 5.

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